fix brown paper bag breakage in t5150-request-pull.sh

The recent addition to the test case 'pull request format' interrupted
the single-quoted text, effectively adding a third argument to the
test_expect_success command. Since we do not have a prerequisite named
"pull request format", the test is skipped, no matter what. Additionally,
the file name argument to the grep command is missing. Fix both issues.
Signed-off-by: NJohannes Sixt <j6t@kdbg.org>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

t/t5150-request-pull.sh

@@ -229,7 +229,7 @@ test_expect_success 'pull request format' '
 		cd local &&
 		git request-pull initial "$downstream_url" full
 	) >request &&
-	grep ' tags/full$'
+	grep " tags/full\$" request
 '
 
 test_expect_success 'request-pull ignores OPTIONS_KEEPDASHDASH poison' '