t6031-test-merge-recursive: do not forget to add file to be committed

Signed-off-by: Stefan Beller <stefanbeller@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: stefanbeller

t/t6031-merge-recursive.sh

@@ -14,6 +14,7 @@ test_expect_success 'mode change in one branch: keep changed version' '
 	git commit -m a &&
 	git checkout -b b1 master &&
 	test_chmod +x file1 &&
+	git add file1 &&
 	git commit -m b1 &&
 	git checkout a1 &&
 	git merge-recursive master -- a1 b1 &&