t4150: am --resolved fails if index has unmerged entries

Since c1d1128 (git-am --resolved: more usable error message.,
2006-04-28), git-am --resolved will check to see if there are any
unmerged entries, and will error out with a user-friendly error message
if there are.

Add a test for this.

Reviewed-by: Stefan Beller <sbeller@google.com>
Reviewed-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Paul Tan <pyokagan@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t4150-am.sh

@@ -437,6 +437,19 @@ test_expect_success 'am --resolved fails if index has no changes' '
 	test_cmp_rev lorem2^^ HEAD
 '
 
+test_expect_success 'am --resolved fails if index has unmerged entries' '
+	rm -fr .git/rebase-apply &&
+	git reset --hard &&
+	git checkout second &&
+	test_must_fail git am -3 lorem-move.patch &&
+	test_path_is_dir .git/rebase-apply &&
+	test_cmp_rev second HEAD &&
+	test_must_fail git am --resolved >err &&
+	test_path_is_dir .git/rebase-apply &&
+	test_cmp_rev second HEAD &&
+	test_i18ngrep "still have unmerged paths" err
+'
+
 test_expect_success 'am takes patches from a Pine mailbox' '
 	rm -fr .git/rebase-apply &&
 	git reset --hard &&