t2026 needs procondition SANITY

When running t0026 as root 'prune directories with unreadable gitdir' fails. Skip this test if SANITY is not set (the use of POSIXPERM is wrong here)

---

Here is the promised patch, on top of pu:

The fix of t0026 is unrelated to all other patches, I think.

The advantage of the series is that it has been tested on CYGWIN/MINGW/Mac/Linux/root@Mac, root@Linux, the disadvantage may be that the commit message may need improvements.

 t/t2026-prune-linked-checkouts.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

index 170aefe..2936d52 100755
@@ -33,7 +33,7 @@ EOF
 	! test -d .git/worktrees
 '
 
-test_expect_success POSIXPERM 'prune directories with unreadable gitdir' '
+test_expect_success SANITY 'prune directories with unreadable gitdir' '
 	mkdir -p .git/worktrees/def/abc &&
 	: >.git/worktrees/def/def &&
 	: >.git/worktrees/def/gitdir &&

2.2.0.rc1.26.g3e3a70d