rebase -r: fix merge -c with a merge strategy

If a rebase is started with a --strategy option other than "ort" or
"recursive" then "merge -c" does not allow the user to reword the
commit message.

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

sequencer.c

@@ -3934,7 +3934,10 @@ static int do_merge(struct repository *r,
 				strvec_pushf(&cmd.args,
 					     "-X%s", opts->xopts[k]);
 		}
-		strvec_push(&cmd.args, "--no-edit");
+		if (!(flags & TODO_EDIT_MERGE_MSG))
+			strvec_push(&cmd.args, "--no-edit");
+		else
+			strvec_push(&cmd.args, "--edit");
 		strvec_push(&cmd.args, "--no-ff");
 		strvec_push(&cmd.args, "--no-log");
 		strvec_push(&cmd.args, "--no-stat");

t/t3430-rebase-merges.sh

@@ -187,6 +187,24 @@ test_expect_success 'merge -c commits before rewording and reloads todo-list' '
 	check_reworded_commits E H
 '
 
+test_expect_success 'merge -c rewords when a strategy is given' '
+	git checkout -b merge-c-with-strategy H &&
+	write_script git-merge-override <<-\EOF &&
+	echo overridden$1 >G.t
+	git add G.t
+	EOF
+
+	PATH="$PWD:$PATH" \
+	GIT_SEQUENCE_EDITOR="echo merge -c H G >" \
+	GIT_EDITOR="echo edited >>" \
+		git rebase --no-ff -ir -s override -Xxopt E &&
+	test_write_lines overridden--xopt >expect &&
+	test_cmp expect G.t &&
+	test_write_lines H "" edited "" >expect &&
+	git log --format=%B -1 >actual &&
+	test_cmp expect actual
+
+'
 test_expect_success 'with a branch tip that was cherry-picked already' '
 	git checkout -b already-upstream main &&
 	base="$(git rev-parse --verify HEAD)" &&