rebase: fix GIT_REFLOG_ACTION regression

The scripted version of "rebase" honored the `GIT_REFLOG_ACTION`,
and some automation scripts expected the reflog entries to be
prefixed with "rebase -i", not "rebase", after running "rebase -i".
This regressed in the reimplementation in C.

Fix that, and add a regression test, both with `GIT_REFLOG_ACTION`
set and unset.

Note: the reflog message for "rebase finished" did *not* honor
GIT_REFLOG_ACTION, and as we are very late in the v2.20.0-rcN phase,
we leave that bug for later (as it seems that that bug has been with
us from the very beginning).

Reported by Ian Jackson.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 26 insertions, 0 deletions

diff --git a/t/t3406-rebase-message.sh b/t/t3406-rebase-message.sh
index 38bd876cab..db8505eb86 100755
--- a/t/t3406-rebase-message.sh
+++ b/t/t3406-rebase-message.sh
@@ -91,4 +91,30 @@ test_expect_success 'error out early upon -C<n> or --whitespace=<bad>' '
 	test_i18ngrep "Invalid whitespace option" err
 '
 
+test_expect_success 'GIT_REFLOG_ACTION' '
+	git checkout start &&
+	test_commit reflog-onto &&
+	git checkout -b reflog-topic start &&
+	test_commit reflog-to-rebase &&
+
+	git rebase reflog-onto &&
+	git log -g --format=%gs -3 >actual &&
+	cat >expect <<-\EOF &&
+	rebase finished: returning to refs/heads/reflog-topic
+	rebase: reflog-to-rebase
+	rebase: checkout reflog-onto
+	EOF
+	test_cmp expect actual &&
+
+	git checkout -b reflog-prefix reflog-to-rebase &&
+	GIT_REFLOG_ACTION=change-the-reflog git rebase reflog-onto &&
+	git log -g --format=%gs -3 >actual &&
+	cat >expect <<-\EOF &&
+	rebase finished: returning to refs/heads/reflog-prefix
+	change-the-reflog: reflog-to-rebase
+	change-the-reflog: checkout reflog-onto
+	EOF
+	test_cmp expect actual
+'
+
 test_done