git-commit: Add tests for invalid usage of -a/--interactive with paths

git-commit was/is broken in that it accepts paths together with -a or
--interactive, which it shouldn't. There tests check those usage errors.

Signed-off-by: Björn Steinbrink <B.Steinbrink@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t7501-commit.sh

@@ -33,6 +33,16 @@ test_expect_failure \
 	"invalid options 2" \
 	"git-commit -C HEAD -m illegal"
 
+test_expect_failure \
+	"using paths with -a" \
+	"echo King of the bongo >file &&
+	git-commit -m foo -a file"
+
+test_expect_failure \
+	"using paths with --interactive" \
+	"echo bong-o-bong >file &&
+	echo 7 | git-commit -m foo --interactive file"
+
 test_expect_failure \
 	"using invalid commit with -C" \
 	"git-commit -C bogus"