t5516: test pushing a tag of an otherwise unreferenced blob

It's not unreasonable to have a tag that points to a blob
that is not part of the normal history. We do this in
git.git to distribute gpg keys. However, we never explicitly
checked in our test suite that this actually works (i.e.,
that pack-objects actually sends the blob because of the tag
mentioning it).

It does in fact work fine, but a recent patch under
discussion broke this, and the test suite didn't notice.
Let's make the test suite more complete.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

t/t5516-fetch-push.sh

@@ -1277,4 +1277,17 @@ EOF
 	git push --no-thin --receive-pack="$rcvpck" no-thin/.git refs/heads/master:refs/heads/foo
 '
 
+test_expect_success 'pushing a tag pushes the tagged object' '
+	rm -rf dst.git &&
+	blob=$(echo unreferenced | git hash-object -w --stdin) &&
+	git tag -m foo tag-of-blob $blob &&
+	git init --bare dst.git &&
+	git push dst.git tag-of-blob &&
+	# the receiving index-pack should have noticed
+	# any problems, but we double check
+	echo unreferenced >expect &&
+	git --git-dir=dst.git cat-file blob tag-of-blob >actual &&
+	test_cmp expect actual
+'
+
 test_done