t1409: use test_path_is_missing()

The test_must_fail() function should only be used for git commands since
we should assume that external commands work sanely. Replace
`test_must_fail test -f` with `test_path_is_missing` since we expect
these paths to not exist.

Signed-off-by: Denton Liu <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: Denton-L

t/t1409-avoid-packing-refs.sh

@@ -27,15 +27,15 @@ test_expect_success 'setup' '
 '
 
 test_expect_success 'do not create packed-refs file gratuitously' '
-	test_must_fail test -f .git/packed-refs &&
+	test_path_is_missing .git/packed-refs &&
 	git update-ref refs/heads/foo $A &&
-	test_must_fail test -f .git/packed-refs &&
+	test_path_is_missing .git/packed-refs &&
 	git update-ref refs/heads/foo $B &&
-	test_must_fail test -f .git/packed-refs &&
+	test_path_is_missing .git/packed-refs &&
 	git update-ref refs/heads/foo $C $B &&
-	test_must_fail test -f .git/packed-refs &&
+	test_path_is_missing .git/packed-refs &&
 	git update-ref -d refs/heads/foo &&
-	test_must_fail test -f .git/packed-refs
+	test_path_is_missing .git/packed-refs
 '
 
 test_expect_success 'check that marking the packed-refs file works' '