upload-pack: read config when serving protocol v2

The upload-pack code paths never call git_config() with
upload_pack_config() when protocol v2 is used, causing options like
uploadpack.packobjectshook to not take effect. Ensure that this function
is called.

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

t/t5702-protocol-v2.sh

@@ -201,6 +201,20 @@ test_expect_success 'ref advertisment is filtered during fetch using protocol v2
 	! grep "refs/tags/three" log
 '
 
+test_expect_success 'upload-pack respects config using protocol v2' '
+	git init server &&
+	write_script server/.git/hook <<-\EOF &&
+		touch hookout
+		"$@"
+	EOF
+	test_commit -C server one &&
+
+	test_config_global uploadpack.packobjectshook ./hook &&
+	test_path_is_missing server/.git/hookout &&
+	git -c protocol.version=2 clone "file://$(pwd)/server" client &&
+	test_path_is_file server/.git/hookout
+'
+
 # Test protocol v2 with 'http://' transport
 #
 . "$TEST_DIRECTORY"/lib-httpd.sh

upload-pack.c

@@ -1376,6 +1376,8 @@ int upload_pack_v2(struct repository *r, struct argv_array *keys,
 	enum fetch_state state = FETCH_PROCESS_ARGS;
 	struct upload_pack_data data;
 
+	git_config(upload_pack_config, NULL);
+
 	upload_pack_data_init(&data);
 	use_sideband = LARGE_PACKET_MAX;