repo-settings: fix checking for fetch.negotiationAlgorithm=default

This regression is not new in v2.35; it first appeared in v2.34. So, not urgent.

Changes since v3:

* 'consecutive' is used as the traditional default. 'default' means either 'consecutive' or 'skipping' depending on feature.experimental.

Changes since v2:

* Also fix the fact that fetch.negotationAlgorithm=$BOGUS_VALUE no longer errors out (yet another regression, this one dating back to v2.24.0), and add a test to make sure we don't regress it again.
* Add 'consecutive' as a synonym for 'default', and remove 'default' from the documentation to guide people towards using 'consecutive' when they want the classic behavior.

Changes since v1:

* Put the common code in two testcases into a function, and then just invoked it from each

Elijah Newren (3):
repo-settings: fix checking for fetch.negotiationAlgorithm=default
repo-settings: fix error handling for unknown values
repo-settings: rename the traditional default
fetch.negotiationAlgorithm

 Documentation/config/fetch.txt | 25 +++++++++++++------------
 fetch-negotiator.c             |  2 +-
 repo-settings.c                |  9 ++++++++-
 repository.h                   |  2 +-
 t/t5500-fetch-pack.sh          | 24 +++++++++++++++++++++---
 5 files changed, 44 insertions(+), 18 deletions(-)

base-commit: 89bece5c8c96f0b962cfc89e63f82d603fd60bed
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1131%2Fnewren%2Ffix-fetch-negotiation-algorithm-equals-default-v4
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1131/newren/fix-fetch-negotiation-algorithm-equals-default-v4
Pull-Request: https://github.com/gitgitgadget/git/pull/1131

Range-diff vs v3:

 1:  df0ec5ffe98 = 1:  df0ec5ffe98 repo-settings: fix checking for fetch.negotiationAlgorithm=default
 2:  23f692b81be = 2:  23f692b81be repo-settings: fix error handling for unknown values
 3:  7b28c527a90 ! 3:  7500a4d2e44 repo-settings: name the default fetch.negotiationAlgorithm 'consecutive'

@@ Metadata
Author: Elijah Newren <[email protected]>

## Commit message ##
- repo-settings: name the default fetch.negotiationAlgorithm 'consecutive'
+ repo-settings: rename the traditional default fetch.negotiationAlgorithm

- Give the default fetch.negotiationAlgorithm the name 'consecutive' and
- update the documentation accordingly. Since there may be some users
- using the name 'default' for this behavior, retain that name for now.
- We do not want to use that name indefinitely, though, because if
- 'skipping' becomes the default, then the "default" behavior will not be
- the default behavior, which would be confusing.
+ Give the traditional default fetch.negotiationAlgorithm the name
+ 'consecutive'. Also allow a choice of 'default' to have Git decide
+ between the choices (currently, picking 'skipping' if
+ feature.experimental is true and 'consecutive' otherwise). Update the
+ documentation accordingly.

@@ Documentation/config/fetch.txt: fetch.output::
- that never skips commits (unless the server has acknowledged it or one
- of its descendants). If feature.experimental is enabled, then this
- setting defaults to "skipping".
+- Unknown values will cause 'git fetch' to error out.
+ Control how information about the commits in the local repository
+ is sent when negotiating the contents of the packfile to be sent by
+ the server. Set to "consecutive" to use an algorithm that walks
@@ Documentation/config/fetch.txt: fetch.output::
+ faster, but may result in a larger-than-necessary packfile; or set
+ to "noop" to not send any information at all, which will almost
+ certainly result in a larger-than-necessary packfile, but will skip
-+ the negotiation step. The default is normally "consecutive", but
-+ if feature.experimental is true, then the default is "skipping".
- Unknown values will cause 'git fetch' to error out.
++ the negotiation step. Set to "default" to override settings made
++ previously and use the default behaviour. The default is normally
++ "consecutive", but if feature.experimental is true, then the
++ default is "skipping". Unknown values will cause 'git fetch' to
++ error out.
+
See also the --negotiate-only and --negotiation-tip options to
+ linkgit:git-fetch[1].

## fetch-negotiator.c ##
@@ fetch-negotiator.c: void fetch_negotiator_init(struct repository *r,
@@ repo-settings.c: void prepare_repo_settings(struct repository *r)
/* Booleans config or default, cascades to other settings */ repo_cfg_bool(r, "feature.manyfiles", &manyfiles, 0);
@@ repo-settings.c: void prepare_repo_settings(struct repository *r)
+ }
+
+ if (!repo_config_get_string(r, "fetch.negotiationalgorithm", &strval)) {
++ int fetch_default = r->settings.fetch_negotiation_algorithm;
+ if (!strcasecmp(strval, "skipping"))
r->settings.fetch_negotiation_algorithm = FETCH_NEGOTIATION_SKIPPING;
else if (!strcasecmp(strval, "noop"))
r->settings.fetch_negotiation_algorithm = FETCH_NEGOTIATION_NOOP;
-- else if (!strcasecmp(strval, "default"))
-- r->settings.fetch_negotiation_algorithm = FETCH_NEGOTIATION_DEFAULT;
-+ else if (!strcasecmp(strval, "consecutive") ||
-+ !strcasecmp(strval, "default"))
++ else if (!strcasecmp(strval, "consecutive"))
+ r->settings.fetch_negotiation_algorithm = FETCH_NEGOTIATION_CONSECUTIVE;
+ else if (!strcasecmp(strval, "default"))
+- r->settings.fetch_negotiation_algorithm = FETCH_NEGOTIATION_DEFAULT;
++ r->settings.fetch_negotiation_algorithm = fetch_default;
else
die("unknown fetch negotiation algorithm '%s'", strval);
}

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