[PATCH v4 4/5] t5520: don't expire reflogs where it matters

["D. Ben Knoble" <ben.knoble@gmail.com>]

From: Thomas Bachem <mail@thomasbachem.com>

The "--rebase -f with rebased upstream" test computes its fork point
from the reflog of refs/remotes/me/copy, and the entry it needs is
the one that the fetch of the test before it wrote. Like every reflog
entry the suite writes after test_tick, it is dated 2005, so the
first "git reflog expire --all" after that fetch removes it. Pull
then finds no fork point and rebases onto the merge head with the
merge head as the upstream, and the rewound commits come back as a
conflict.

Since 452b12c2e0 (builtin/maintenance: use "geometric" strategy by
default, 2026-02-24) auto maintenance runs that expiry once the reflog
of HEAD holds a hundred entries it would remove, the default of
maintenance.reflog-expire.auto. Which run crosses the threshold
depends on the entries and maintenance runs before it, so the script
passed by chance: a stash topic that no longer runs "git reset" from
"stash apply --index" and a rebase topic that runs auto maintenance
at the end of "git rebase" together move the expiry between the two
tests.

Pin the expiry as ea7d894f44 (t34xx: don't expire reflogs where it
matters, 2026-02-24) did for the rebase tests. That covers a "git gc"
as well, which expires reflogs on its own, where turning off the auto
trigger of the reflog-expire task alone would not.

Reported-by: Junio C Hamano <gitster@pobox.com>
Helped-by: D. Ben Knoble <ben.knoble@gmail.com>
Helped-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Assisted-by: Claude Fable 5.1
Signed-off-by: Thomas Bachem <mail@thomasbachem.com>
Signed-off-by: D. Ben Knoble <ben.knoble@gmail.com>
---
 t/t5520-pull.sh | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/t/t5520-pull.sh b/t/t5520-pull.sh
index 27f38ab3c8..bc818605a5 100755
--- a/t/t5520-pull.sh
+++ b/t/t5520-pull.sh
@@ -35,6 +35,12 @@ test_pull_autostash_fail () {
 }
 
 test_expect_success setup '
+	# Commit dates are hardcoded to 2005, and the reflog entries will have
+	# a matching timestamp. Maintenance may thus immediately expire
+	# reflogs if it was running.
+	git config set gc.reflogExpire never &&
+	git config set gc.reflogExpireUnreachable never &&
+
 	echo file >file &&
 	git add file &&
 	git commit -a -m original
-- 
2.56.0.rc1.315.gc6ed9934b7.dirty