sequencer: fix environment that 'exec' commands run under

From: Elijah Newren <[email protected]>

Commands executed from git rebase --exec can give different behavior from within that environment than they would outside of it, due to the fact that sequencer.c exports both GIT_DIR and GIT_WORK_TREE. For example, if the relevant script calls something like

  git -C ../otherdir log --format=%H --no-walk

the user may be surprised to find that the command above does not show a commit hash from ../otherdir, because $GIT_DIR prevents automatic gitdir detection and makes the -C option useless.

This is a regression in behavior from the original legacy implemented-in-shell rebase. It is perhaps rare for it to cause problems in practice, especially since most small problems that were caused by this area of bugs has been fixed-up in the past in a way that masked the particular bug observed without fixing the real underlying problem.

How we arrived at the current situation is perhaps merited. The setting

of GIT_DIR and GIT_WORK_TREE done by sequencer.c arose from a sequence of historical accidents:

* When rebase was implemented as a shell command, it would call git-sh-setup, which among other things would set GIT_DIR -- but not export it. This meant that when rebase --exec commands were run via

      /bin/sh -c "$COMMAND"

they would not inherit the GIT_DIR setting. The fact that GIT_DIR was not set in the run $COMMAND is the behavior we'd like to restore.

* When the rebase--helper builtin was introduced to allow incrementally replacing shell with C code, we were in an implementation that was

half shell, half C. In particular, commit 18633e1a22 ("rebase -i: use the rebase--helper builtin", 2017-02-09) added calls to
exec git rebase--helper ...

which caused rebase--helper to inherit the GIT_DIR environment variable from the shell. git's setup would change the environment variable from an absolute path to a relative one (".git"), but would leave it set. This meant that when rebase --exec commands were run via

      run_command_v_opt(...)

they would inherit the GIT_DIR setting.

* In commit 09d7b6c6fa ("sequencer: pass absolute GIT_DIR to exec commands", 2017-10-31), it was noted that the GIT_DIR caused problems with some commands; e.g.

      git rebase --exec 'cd subdir && git describe' ...
  would have GIT_DIR=.git which was invalid due to the change to the
  subdirectory.  Instead of questioning why GIT_DIR was set, that commit
  instead made sequencer change GIT_DIR to be an absolute path and
  explicitly export it via
      argv_array_pushf(&child_env, "GIT_DIR=%s", absolute_path(get_git_dir()));
      run_command_v_opt_cd_env(..., child_env.argv)

* In commit ab5e67d751 ("sequencer: pass absolute GIT_WORK_TREE to exec commands", 2018-07-14), it was noted that when GIT_DIR is set but GIT_WORK_TREE is not, that we do not discover GIT_WORK_TREE but just assume it is '.'. That is incorrect if trying to run commands from a subdirectory. However, rather than question why GIT_DIR was set, that commit instead also added GIT_WORK_TREE to the list of things to export.

Each of the above problems would have been fixed automatically when git-rebase become a full builtin, had it not been for the fact that

sequencer.c started exporting GIT_DIR and GIT_WORK_TREE in the interim. Stop exporting them now.

Signed-off-by Elijah Newren <[email protected]>

Acked-by Johannes Schindelin <[email protected]>

---
sequencer: fix environment that 'exec' commands run under

I'm not sure if the added regression tests make sense

or if t3409 is the best place to put them (taking over a recently removed t3409 that was used for the deprecated preserve merges option).

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1134%2Fnewren%2Ffix-rebase-exec-environ-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1134/newren/fix-rebase-exec-environ-v1
Pull-Request: https://github.com/git/git/pull/1134

 sequencer.c               |  9 +--------
 t/t3409-rebase-environ.sh | 23 +++++++++++++++++++++++
 2 files changed, 24 insertions(+), 8 deletions(-)
 create mode 100755 t/t3409-rebase-environ.sh

sequencer.c +1 -8

index ea96837cde3..9afdbe3e3d1 100644
@@ -3495,17 +3495,12 @@ static int error_failed_squash(struct repository *r,
 
 static int do_exec(struct repository *r, const char *command_line)
 {
-	struct strvec child_env = STRVEC_INIT;
 	const char *child_argv[] = { NULL, NULL };
 	int dirty, status;
 
 	fprintf(stderr, _("Executing: %s\n"), command_line);
 	child_argv[0] = command_line;
-	strvec_pushf(&child_env, "GIT_DIR=%s", absolute_path(get_git_dir()));
-	strvec_pushf(&child_env, "GIT_WORK_TREE=%s",
-		     absolute_path(get_git_work_tree()));
-	status = run_command_v_opt_cd_env(child_argv, RUN_USING_SHELL, NULL,
-					  child_env.v);
+	status = run_command_v_opt(child_argv, RUN_USING_SHELL);
 
 	/* force re-reading of the cache */
 	if (discard_index(r->index) < 0 || repo_read_index(r) < 0)

@@ -3535,8 +3530,6 @@ static int do_exec(struct repository *r, const char *command_line)
 		status = 1;
 	}
 
-	strvec_clear(&child_env);
-
 	return status;
 }
 

t/t3409-rebase-environ.sh new file +0 -0

new file mode 100755
index 00000000000..83ffb39d9ff

t/t3409-rebase-environ.sh new file +8 -0

+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	test_commit one &&
+	test_commit two &&
+	test_commit three
+'

Quoted 7 lines · Elijah Newren via GitGitGadget

From: Elijah Newren <[email protected]>

Commands executed from git rebase --exec can give different behavior from within that environment than they would outside of it, due to the fact that sequencer.c exports both GIT_DIR and GIT_WORK_TREE. For example, if the relevant script calls something like

Quoted 5 lines

  git -C ../otherdir log --format=%H --no-walk

the user may be surprised to find that the command above does not show a commit hash from ../otherdir, because $GIT_DIR prevents automatic gitdir detection and makes the -C option useless.

Yep. I've had a case where "git rebase -x 'make test'" would fail because "make test" tries to run some Git commands in a temporary repo. The workaround was to unset all GIT_* environment variables, just like t/test-lib.sh does.

I had the same problem when testing shell completion because git prepends $(git --exec-path) to $PATH. I don't see a good reason why "git rebase -x cmd" passes a modified $PATH (and $GIT_EXEC_PATH) to cmd. The user is back in control, so I'd expect the same environment as for the parent rebase process.

AFAICT, the main purpose of changing $PATH is to ease (cross-language) implementation, I don't think the user is meant to notice.
Of course, exporting GIT_EXEC_PATH is desirable for some commands like gc that delegate to a bunch of git processes without user interaction, to make sure all children are from the same build. c90d565a46 (Propagate --exec-path setting to external commands via GIT_EXEC_PATH, 2009-03-21). But I don't think the same applies for rebase -x.

Quoted 6 lines

This is a regression in behavior from the original legacy implemented-in-shell rebase. It is perhaps rare for it to cause problems in practice, especially since most small problems that were caused by this area of bugs has been fixed-up in the past in a way that masked the particular bug observed without fixing the real underlying problem.

Really interesting that we added multiple workarounds, when we just needed to stop polluting the environment. The fact that our test suite unsets most GIT_* variables also masks potential problems.

Quoted 1 line

Quoted 1 line

How we arrived at the current situation is perhaps merited. The setting

This sounds weirdly penitent if read the wrong way. I guess "An explanation how we arrived ... "?

Quoted 10 lines

of GIT_DIR and GIT_WORK_TREE done by sequencer.c arose from a sequence of historical accidents:

* When rebase was implemented as a shell command, it would call git-sh-setup, which among other things would set GIT_DIR -- but not export it. This meant that when rebase --exec commands were run via

      /bin/sh -c "$COMMAND"

they would not inherit the GIT_DIR setting. The fact that GIT_DIR was not set in the run $COMMAND is the behavior we'd like to restore.

Quoted 2 lines

* When the rebase--helper builtin was introduced to allow incrementally replacing shell with C code, we were in an implementation that was

More correct to say "we were in an (implementation) state" or better:
"we had an implementation"?

Quoted 3 lines

half shell, half C. In particular, commit 18633e1a22 ("rebase -i: use the rebase--helper builtin", 2017-02-09) added calls to
exec git rebase--helper ...

Ok I guess this was a good reason for adding the exec-path to the environment of exec steps.

Quoted 27 lines

which caused rebase--helper to inherit the GIT_DIR environment variable from the shell. git's setup would change the environment variable from an absolute path to a relative one (".git"), but would leave it set. This meant that when rebase --exec commands were run via

      run_command_v_opt(...)

they would inherit the GIT_DIR setting.

* In commit 09d7b6c6fa ("sequencer: pass absolute GIT_DIR to exec commands", 2017-10-31), it was noted that the GIT_DIR caused problems with some commands; e.g.

      git rebase --exec 'cd subdir && git describe' ...
  would have GIT_DIR=.git which was invalid due to the change to the
  subdirectory.  Instead of questioning why GIT_DIR was set, that commit
  instead made sequencer change GIT_DIR to be an absolute path and
  explicitly export it via
      argv_array_pushf(&child_env, "GIT_DIR=%s", absolute_path(get_git_dir()));
      run_command_v_opt_cd_env(..., child_env.argv)

* In commit ab5e67d751 ("sequencer: pass absolute GIT_WORK_TREE to exec commands", 2018-07-14), it was noted that when GIT_DIR is set but GIT_WORK_TREE is not, that we do not discover GIT_WORK_TREE but just assume it is '.'. That is incorrect if trying to run commands from a subdirectory. However, rather than question why GIT_DIR was set, that commit instead also added GIT_WORK_TREE to the list of things to export.

Quoted 2 lines

Each of the above problems would have been fixed automatically when git-rebase become a full builtin, had it not been for the fact that

s/become/became/

Quoted 7 lines

sequencer.c started exporting GIT_DIR and GIT_WORK_TREE in the interim. Stop exporting them now.

Signed-off-by Elijah Newren <[email protected]>

Acked-by Johannes Schindelin <[email protected]>

---
sequencer: fix environment that 'exec' commands run under

Maybe: sequencer: do not export GIT_DIR and GIT_WORK_TREE to exec

(assuming that $PATH also needs fixing)

Quoted 2 lines

I'm not sure if the added regression tests make sense

They are simple and correct.
We still pass on values from --git-dir= and GIT_DIR=. git. Those are /probably/ right.

Quoted 2 lines

or if t3409 is the best place to put them (taking over a recently removed t3409 that was used for the deprecated preserve merges option).

Looks like there is no t/t34*-rebase-exec.sh yet. Most tests of --exec are in t/t3404-rebase-interactive.sh, but we don't need the interactive bit here.

Quoted 41 lines

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1134%2Fnewren%2Ffix-rebase-exec-environ-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1134/newren/fix-rebase-exec-environ-v1
Pull-Request: https://github.com/git/git/pull/1134

 sequencer.c               |  9 +--------
 t/t3409-rebase-environ.sh | 23 +++++++++++++++++++++++
 2 files changed, 24 insertions(+), 8 deletions(-)
 create mode 100755 t/t3409-rebase-environ.sh

sequencer.c +1 -8

index ea96837cde3..9afdbe3e3d1 100644
@@ -3495,17 +3495,12 @@ static int error_failed_squash(struct repository *r,
 
 static int do_exec(struct repository *r, const char *command_line)
 {
-     struct strvec child_env = STRVEC_INIT;
      const char *child_argv[] = { NULL, NULL };
      int dirty, status;
 
      fprintf(stderr, _("Executing: %s\n"), command_line);
      child_argv[0] = command_line;
-     strvec_pushf(&child_env, "GIT_DIR=%s", absolute_path(get_git_dir()));
-     strvec_pushf(&child_env, "GIT_WORK_TREE=%s",
-                  absolute_path(get_git_work_tree()));
-     status = run_command_v_opt_cd_env(child_argv, RUN_USING_SHELL, NULL,
-                                       child_env.v);
+     status = run_command_v_opt(child_argv, RUN_USING_SHELL);
 
      /* force re-reading of the cache */
      if (discard_index(r->index) < 0 || repo_read_index(r) < 0)

@@ -3535,8 +3530,6 @@ static int do_exec(struct repository *r, const char *command_line)
              status = 1;
      }
 
-     strvec_clear(&child_env);
-
      return status;
 }
 

t/t3409-rebase-environ.sh line 3

Quoted 9 lines

t/t3409-rebase-environ.sh new file +3 -0

new file mode 100755
index 00000000000..83ffb39d9ff
@@ -0,0 +1,23 @@
+#!/bin/sh
+
+test_description='git rebase interactive environment'

maybe test_description='git rebase --exec environment'

Quoted 8 lines

t/t3409-rebase-environ.sh new file +8 -0

+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+     test_commit one &&
+     test_commit two &&
+     test_commit three
+'

t/t3409-rebase-environ.sh line 21

Quoted 10 lines

t/t3409-rebase-environ.sh new file +10 -0

+
+test_expect_success 'rebase --exec does not muck with GIT_DIR' '
+     git rebase --exec "printf %s \$GIT_DIR >environ" HEAD~1 &&
+     test_must_be_empty environ
+'
+
+test_expect_success 'rebase --exec does not muck with GIT_WORK_TREE' '
+     git rebase --exec "printf %s \$GIT_WORK_TREE >environ" HEAD~1 &&
+     test_must_be_empty environ
+'

I guess we could add a test for existing GIT_DIR in the environment, even if it's not affected

        test_expect_success 'already exported GIT_DIR is passed on to rebase --exec commands' '
                GIT_DIR=.git GIT_WORK_TREE=. git rebase HEAD~1 --exec \
                        "printf %s\\\\n \"\$GIT_DIR\" \"\$GIT_WORK_TREE\" >actual" &&
                cat >expect <<-EOF &&
                .git
                .
                EOF
                test_cmp expect actual &&
                cat actual
        '

(I tried to use non-default values lik ./.git and ./. but the weird thing is that git canonicalizes the worktree but not the git dir, so meh)

I also wasn't sure about the behavior of --git-dir= Should it be the same as GIT_DIR=? I think it's also conceivable that --git-dir= does *not* cause GIT_DIR to be exported to exec commands, though that might break existing
scripts. Something like

        git --work-tree=../other-worktree --git-dir=../other-worktree/.git \
                rebase --exec "make generate-documentation && git commit -a --amend --no-edit"

(needless to say that in this case "git -C ../other-worktree" is probably what the user wants)

// Resending this email from 8 days ago; Dscho pointed that I accidentally // responded to the GitHub PR email instead of the original email, and // while Johannes already said he likes my V2, perhaps there are other // comments here that benefit other current or future reviewers

Hi Johannes,

Thanks for looking over the patch and commit message closely; very cool.

Quoted 24 lines · Johannes Altmanninger

Quoted 7 lines · Elijah Newren via GitGitGadget

From: Elijah Newren <[email protected]>

Commands executed from git rebase --exec can give different behavior from within that environment than they would outside of it, due to the fact that sequencer.c exports both GIT_DIR and GIT_WORK_TREE. For example, if the relevant script calls something like

Quoted 5 lines

  git -C ../otherdir log --format=%H --no-walk

the user may be surprised to find that the command above does not show a commit hash from ../otherdir, because $GIT_DIR prevents automatic gitdir detection and makes the -C option useless.

Yep. I've had a case where "git rebase -x 'make test'" would fail because "make test" tries to run some Git commands in a temporary repo. The workaround was to unset all GIT_* environment variables, just like t/test-lib.sh does.

I had the same problem when testing shell completion because git prepends $(git --exec-path) to $PATH. I don't see a good reason why "git rebase -x cmd" passes a modified $PATH (and $GIT_EXEC_PATH) to cmd. The user is back in control, so I'd expect the same environment as for the parent rebase process.

Quoted 7 lines

AFAICT, the main purpose of changing $PATH is to ease (cross-language) implementation, I don't think the user is meant to notice.
Of course, exporting GIT_EXEC_PATH is desirable for some commands like gc that delegate to a bunch of git processes without user interaction, to make sure all children are from the same build. c90d565a46 (Propagate --exec-path setting to external commands via GIT_EXEC_PATH, 2009-03-21). But I don't think the same applies for rebase -x.

Well, rebase does actually delegate to other git processes -- git commit (in some cases), git stash (if --autostash is specified), git merge (when a non-default, non-built-in strategy is selected), running the post-rewrite hook (if it exists), and indirectly through git commit all the various hooks it might call, and when calling git-stash the huge pile of subcommands it invokes.

Some of those should definitely be replaced with library calls instead of forking a subprocess. And I'm sure the PATH/EXEC_PATH could be made specific to the places that really need it, but it's so much easier to just make one global replacement and it avoids people forgetting to do so before calling subcommands that then might run the wrong git version in a different setup. So, I'm a bit conflicted about fixing PATH/EXEC_PATH right away. Perhaps if we just modified those back to their original value just the for --exec'd command?

That probably deserves a series all of its own, but might be interesting for someone else to look at.
...
the following passes:

test_expect_success 'setup alternate GIT_DIR and GIT_WORK_TREE' '
git clone . other-copy &&
git worktree add other-worktree
'

test_expect_success 'already exported GIT_DIR is passed on to rebase --exec commands' '

    test_when_finished "rm other-worktree/actual" &&

    GIT_DIR=other-copy/.git GIT_WORK_TREE=other-worktree \
        git rebase HEAD~1 --exec \
        "printf %s\\\\n \"\$GIT_DIR\" \"\$GIT_WORK_TREE\" \"\$PWD\" >actual" &&

    cat >expect <<-EOF &&
    $(cd other-copy && pwd -P)/.git
    .
    $(cd other-worktree && pwd -P)
    EOF

    test_cmp expect other-worktree/actual

'

I don't know if that's correct or buggy

but it's starting to stray
from what I was intending to test so I might leave it out.

Quoted 8 lines

I also wasn't sure about the behavior of --git-dir= Should it be the same as GIT_DIR=? I think it's also conceivable that --git-dir= does *not* cause GIT_DIR to be exported to exec commands, though that might break existing
scripts. Something like

        git --work-tree=../other-worktree --git-dir=../other-worktree/.git \
                rebase --exec "make generate-documentation && git commit -a --amend --no-edit"

Quoted 2 lines

(needless to say that in this case "git -C ../other-worktree" is probably what the user wants)

It sets the variables; the following passes (which differs from above only in using --git-dir and --work-tree rather than GIT_DIR and GIT_WORK_TREE):

sequencer: fix environment that 'exec' commands run under

Changes since v1:

* Fix wording in multiple locations pointed out by Johannes Altmanninger

Note that Johaness Altmanninger also suggested some additional GIT_DIR/GIT_WORK_TREE and --git-dir/--work-tree testcases, but since those change the current working directory to the work tree so that GIT_WORK_TREE ends up being '.' in every case, I think it's straying a bit from the point of the test. If other feel strongly, I can add them in.

From: Elijah Newren <[email protected]>

Commands executed from git rebase --exec can give different behavior from within that environment than they would outside of it, due to the fact that sequencer.c exports both GIT_DIR and GIT_WORK_TREE. For example, if the relevant script calls something like

   git -C ../otherdir log --format=%H --no-walk

the user may be surprised to find that the command above does not show a commit hash from ../otherdir, because $GIT_DIR prevents automatic gitdir detection and makes the -C option useless.

This is a regression in behavior from the original legacy implemented-in-shell rebase. It is perhaps rare for it to cause problems in practice, especially since most small problems that were caused by this area of bugs has been fixed-up in the past in a way that masked the particular bug observed without fixing the real underlying problem.

An explanation of how we arrived at the current situation is perhaps merited. The setting of GIT_DIR and GIT_WORK_TREE done by sequencer.c arose from a sequence of historical accidents:

* When rebase was implemented as a shell command, it would call git-sh-setup, which among other things would set GIT_DIR -- but not export it. This meant that when rebase --exec commands were run via

       /bin/sh -c "$COMMAND"

they would not inherit the GIT_DIR setting. The fact that GIT_DIR was not set in the run $COMMAND is the behavior we'd like to restore.

* When the rebase--helper builtin was introduced to allow incrementally replacing shell with C code, we had an implementation that was half shell, half C. In particular, commit 18633e1a22 ("rebase -i: use the rebase--helper builtin", 2017-02-09) added calls to
exec git rebase--helper ...
which caused rebase--helper to inherit the GIT_DIR environment variable from the shell. git's setup would change the environment variable from an absolute path to a relative one (".git"), but would leave it set. This meant that when rebase --exec commands were run via

       run_command_v_opt(...)

they would inherit the GIT_DIR setting.

* In commit 09d7b6c6fa ("sequencer: pass absolute GIT_DIR to exec commands", 2017-10-31), it was noted that the GIT_DIR caused problems with some commands; e.g.

       git rebase --exec 'cd subdir && git describe' ...
   would have GIT_DIR=.git which was invalid due to the change to the
   subdirectory.  Instead of questioning why GIT_DIR was set, that commit
   instead made sequencer change GIT_DIR to be an absolute path and
   explicitly export it via
       argv_array_pushf(&child_env, "GIT_DIR=%s", absolute_path(get_git_dir()));
       run_command_v_opt_cd_env(..., child_env.argv)

* In commit ab5e67d751 ("sequencer: pass absolute GIT_WORK_TREE to exec commands", 2018-07-14), it was noted that when GIT_DIR is set but GIT_WORK_TREE is not, that we do not discover GIT_WORK_TREE but just assume it is '.'. That is incorrect if trying to run commands from a subdirectory. However, rather than question why GIT_DIR was set, that commit instead also added GIT_WORK_TREE to the list of things to export.

Each of the above problems would have been fixed automatically when git-rebase became a full builtin, had it not been for the fact that sequencer.c started exporting GIT_DIR and GIT_WORK_TREE in the interim. Stop exporting them now.

Signed-off-by Elijah Newren <[email protected]>

Acked-by Johannes Schindelin <[email protected]>

---
sequencer: fix environment that 'exec' commands run under

Changes since v1:

* Fix wording in multiple locations pointed out by Johannes Altmanninger

Note that Johaness Altmanninger also suggested some additional GIT_DIR/GIT_WORK_TREE and --git-dir/--work-tree testcases, but since those change the current working directory to the work tree so that GIT_WORK_TREE ends up being '.' in every case, I think it's straying a bit from the point of the test. If other feel strongly, I can add them in.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1134%2Fnewren%2Ffix-rebase-exec-environ-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1134/newren/fix-rebase-exec-environ-v2
Pull-Request: https://github.com/git/git/pull/1134

Range-diff vs v1:

1: 12713c83705 ! 1: c647c45375a sequencer: fix environment that 'exec' commands run under
@@ Metadata
Author: Elijah Newren <[email protected]>

## Commit message ##
- sequencer: fix environment that 'exec' commands run under
+ sequencer: do not export GIT_DIR and GIT_WORK_TREE for 'exec'

Commands executed from git rebase --exec can give different behavior from within that environment than they would outside of it, due to the
@@ Commit message
masked the particular bug observed without fixing the real underlying problem.

- How we arrived at the current situation is perhaps merited. The setting
- of GIT_DIR and GIT_WORK_TREE done by sequencer.c arose from a sequence
- of historical accidents:
+ An explanation of how we arrived at the current situation is perhaps
+ merited. The setting of GIT_DIR and GIT_WORK_TREE done by sequencer.c
+ arose from a sequence of historical accidents:

* When rebase was implemented as a shell command, it would call git-sh-setup, which among other things would set GIT_DIR -- but not
@@ Commit message
was not set in the run $COMMAND is the behavior we'd like to restore.

* When the rebase--helper builtin was introduced to allow incrementally
- replacing shell with C code, we were in an implementation that was
- half shell, half C. In particular, commit 18633e1a22 ("rebase -i: use
- the rebase--helper builtin", 2017-02-09) added calls to
+ replacing shell with C code, we had an implementation that was half
+ shell, half C. In particular, commit 18633e1a22 ("rebase -i: use the
+ rebase--helper builtin", 2017-02-09) added calls to
exec git rebase--helper ...
which caused rebase--helper to inherit the GIT_DIR environment variable from the shell. git's setup would change the environment
@@ Commit message
export.

Each of the above problems would have been fixed automatically when
- git-rebase become a full builtin, had it not been for the fact that
+ git-rebase became a full builtin, had it not been for the fact that
sequencer.c started exporting GIT_DIR and GIT_WORK_TREE in the interim. Stop exporting them now.

  sequencer.c               |  9 +--------
  t/t3409-rebase-environ.sh | 23 +++++++++++++++++++++++
  2 files changed, 24 insertions(+), 8 deletions(-)

create mode 100755 t/t3409-rebase-environ.sh

sequencer.c +1 -8

index ea96837cde3..9afdbe3e3d1 100644
@@ -3495,17 +3495,12 @@ static int error_failed_squash(struct repository *r,
 
  static int do_exec(struct repository *r, const char *command_line)
  {
-	struct strvec child_env = STRVEC_INIT;
  	const char *child_argv[] = { NULL, NULL };
  	int dirty, status;
 
  	fprintf(stderr, _("Executing: %s\n"), command_line);
  	child_argv[0] = command_line;
-	strvec_pushf(&child_env, "GIT_DIR=%s", absolute_path(get_git_dir()));
-	strvec_pushf(&child_env, "GIT_WORK_TREE=%s",
-		     absolute_path(get_git_work_tree()));
-	status = run_command_v_opt_cd_env(child_argv, RUN_USING_SHELL, NULL,
-					  child_env.v);
+	status = run_command_v_opt(child_argv, RUN_USING_SHELL);
 
  	/* force re-reading of the cache */
  	if (discard_index(r->index) < 0 || repo_read_index(r) < 0)

@@ -3535,8 +3530,6 @@ static int do_exec(struct repository *r, const char *command_line)
  		status = 1;
  	}
 
-	strvec_clear(&child_env);
-
  	return status;
  }
 

t/t3409-rebase-environ.sh new file +23 -0

new file mode 100755
index 00000000000..83ffb39d9ff
@@ -0,0 +1,23 @@
+#!/bin/sh
+
+test_description='git rebase interactive environment'
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	test_commit one &&
+	test_commit two &&
+	test_commit three
+'
+
+test_expect_success 'rebase --exec does not muck with GIT_DIR' '
+	git rebase --exec "printf %s \$GIT_DIR >environ" HEAD~1 &&
+	test_must_be_empty environ
+'
+
+test_expect_success 'rebase --exec does not muck with GIT_WORK_TREE' '
+	git rebase --exec "printf %s \$GIT_WORK_TREE >environ" HEAD~1 &&
+	test_must_be_empty environ
+'
+
+test_done

base-commit: 88d915a634b449147855041d44875322de2b286d