Merge branch 'dd/t5703-grep-a-fix'

Update an unconditional use of "grep -a" with a perl script in a test.

* dd/t5703-grep-a-fix:
  t5703: replace "grep -a" usage by perl
diff --git a/t/t5703-upload-pack-ref-in-want.sh b/t/t5703-upload-pack-ref-in-want.sh
index a34460f..92ad5ee 100755
--- a/t/t5703-upload-pack-ref-in-want.sh
+++ b/t/t5703-upload-pack-ref-in-want.sh
@@ -49,15 +49,18 @@
 
 test_expect_success 'config controls ref-in-want advertisement' '
 	test-tool serve-v2 --advertise-capabilities >out &&
-	! grep -a ref-in-want out &&
+	perl -ne "/ref-in-want/ and print" out >out.filter &&
+	test_must_be_empty out.filter &&
 
 	git config uploadpack.allowRefInWant false &&
 	test-tool serve-v2 --advertise-capabilities >out &&
-	! grep -a ref-in-want out &&
+	perl -ne "/ref-in-want/ and print" out >out.filter &&
+	test_must_be_empty out.filter &&
 
 	git config uploadpack.allowRefInWant true &&
 	test-tool serve-v2 --advertise-capabilities >out &&
-	grep -a ref-in-want out
+	perl -ne "/ref-in-want/ and print" out >out.filter &&
+	test_file_not_empty out.filter
 '
 
 test_expect_success 'invalid want-ref line' '