t1503: fix broken test_must_fail calls

Some tests in maint-reflog-beyond-horizon are calling test_must_fail
in such a way that the arguments to test_must_fail do, indeed, fail
but not in the manner expected by the test.

This patch removes the unnecessary and unhelpful double quotes.

Signed-off-by: Jon Seymour <jon.seymour@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t1503-rev-parse-verify.sh

@@ -111,8 +111,8 @@ test_expect_success 'master@{n} for various n' '
 	git rev-parse --verify master@{0} &&
 	git rev-parse --verify master@{1} &&
 	git rev-parse --verify master@{$Nm1} &&
-	test_must_fail "git rev-parse --verify master@{$N}" &&
-	test_must_fail "git rev-parse --verify master@{$Np1}"
+	test_must_fail git rev-parse --verify master@{$N} &&
+	test_must_fail git rev-parse --verify master@{$Np1}
 '
 
 test_done