ls-refs: filter refs using namespace-stripped name

If a user fetches refs/heads/master from a repo with namespace "ns", the
remote is expected to (1) not send the real refs/heads/master, and (2)
send refs/namespaces/ns/refs/heads/master with the name
refs/heads/master. (1) indeed happens now, but not (2) - Git only sends
refs that have the user-given prefix, but it checks them against the
full name of the ref (the one starting with refs/namespaces), and not
the namespace-stripped one.

This is demonstrated by the patch in the test. Currently, it results in
"fatal: couldn't find remote ref refs/heads/master" despite both
unnamespaced and namespaced master being present. With the code change,
it produces the expected result.

Check the ref prefixes against the namespace-stripped name.

This bug was discovered through applying patches [1] that override
protocol.version to 2 in repositories when running tests, allowing us to
notice differences in behavior across different protocol versions.

[1] https://public-inbox.org/git/cover.1547677183.git.jonathantanmy@google.com/

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/t/t5702-protocol-v2.sh b/t/t5702-protocol-v2.sh
index 0f2b09ebb8..3d802aa587 100755
--- a/t/t5702-protocol-v2.sh
+++ b/t/t5702-protocol-v2.sh
@@ -514,6 +514,27 @@ test_expect_success 'fetch with http:// using protocol v2' '
 	grep "git< version 2" log
 '
 
+test_expect_success 'fetch from namespaced repo respects namespaces' '
+	test_when_finished "rm -f log" &&
+
+	git init "$HTTPD_DOCUMENT_ROOT_PATH/nsrepo" &&
+	test_commit -C "$HTTPD_DOCUMENT_ROOT_PATH/nsrepo" one &&
+	test_commit -C "$HTTPD_DOCUMENT_ROOT_PATH/nsrepo" two &&
+	git -C "$HTTPD_DOCUMENT_ROOT_PATH/nsrepo" \
+		update-ref refs/namespaces/ns/refs/heads/master one &&
+
+	GIT_TRACE_PACKET="$(pwd)/log" git -C http_child -c protocol.version=2 \
+		fetch "$HTTPD_URL/smart_namespace/nsrepo" \
+		refs/heads/master:refs/heads/theirs &&
+
+	# Server responded using protocol v2
+	grep "fetch< version 2" log &&
+
+	git -C "$HTTPD_DOCUMENT_ROOT_PATH/nsrepo" rev-parse one >expect &&
+	git -C http_child rev-parse theirs >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'push with http:// and a config of v2 does not request v2' '
 	test_when_finished "rm -f log" &&
 	# Till v2 for push is designed, make sure that if a client has