[PATCH v4 2/8] rebase --apply: improve fast-forward reflog message

["Phillip Wood via GitGitGadget" <gitgitgadget@gmail.com>]

From: Phillip Wood <phillip.wood@dunelm.org.uk>

Using move_to_original_branch() when reattaching HEAD after a
fast-forward improves HEAD's reflog message when rebasing a branch. This
is because it uses separate reflog messages for "HEAD" and
"branch". HEAD's reflog will now record which branch we're returning to.

When rebasing a detached HEAD there is no change in behavior. We
currently call reset_head() when head_name is NULL but
move_to_original_branch() does not. However the existing call does not
add a message to the reflog because we're not changing the commit that
HEAD points to and so lock_ref_for_update() skips the update.

Note that the removal of "strbuf_reset(&msg)" is safe as there is a call
to strbuf_release(&msf) just above this hunk which can be seen by
viewing the diff with -U6.

Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
---
 builtin/rebase.c          | 11 +----------
 t/t3406-rebase-message.sh |  8 +-------
 2 files changed, 2 insertions(+), 17 deletions(-)

diff --git a/builtin/rebase.c b/builtin/rebase.c
index ef520f66fb8..e67020b3586 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -1811,19 +1811,10 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 	 * If the onto is a proper descendant of the tip of the branch, then
 	 * we just fast-forwarded.
 	 */
-	strbuf_reset(&msg);
 	if (oideq(&branch_base, &options.orig_head->object.oid)) {
 		printf(_("Fast-forwarded %s to %s.\n"),
 			branch_name, options.onto_name);
-		strbuf_addf(&msg, "rebase finished: %s onto %s",
-			options.head_name ? options.head_name : "detached HEAD",
-			oid_to_hex(&options.onto->object.oid));
-		memset(&ropts, 0, sizeof(ropts));
-		ropts.branch = options.head_name;
-		ropts.flags = RESET_HEAD_REFS_ONLY;
-		ropts.head_msg = msg.buf;
-		reset_head(the_repository, &ropts);
-		strbuf_release(&msg);
+		move_to_original_branch(&options);
 		ret = finish_rebase(&options);
 		goto cleanup;
 	}
diff --git a/t/t3406-rebase-message.sh b/t/t3406-rebase-message.sh
index 413d6132ea2..5253dd1551d 100755
--- a/t/t3406-rebase-message.sh
+++ b/t/t3406-rebase-message.sh
@@ -143,14 +143,8 @@ test_reflog () {
 	) &&
 
 	git log -g --format=%gs -2 >actual &&
-	if test "$mode" = "--apply"
-	then
-		finish_msg="refs/heads/fast-forward onto $(git rev-parse main)"
-	else
-		finish_msg="returning to refs/heads/fast-forward"
-	fi &&
 	write_reflog_expect <<-EOF &&
-	${reflog_action:-rebase} (finish): $finish_msg
+	${reflog_action:-rebase} (finish): returning to refs/heads/fast-forward
 	${reflog_action:-rebase} (start): checkout main
 	EOF
 	test_cmp expect actual &&
-- 
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