push: pass ref prefixes when pushing

Construct a list of ref prefixes to be passed to 'get_refs_list()' from
the refspec to be used during the push.  This list of ref prefixes will
be used to allow the server to filter the ref advertisement when
communicating using protocol v2.

Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

transport.c

@@ -1028,11 +1028,38 @@ int transport_push(struct transport *transport,
 		int porcelain = flags & TRANSPORT_PUSH_PORCELAIN;
 		int pretend = flags & TRANSPORT_PUSH_DRY_RUN;
 		int push_ret, ret, err;
+		struct refspec *tmp_rs;
+		struct argv_array ref_prefixes = ARGV_ARRAY_INIT;
+		int i;
 
 		if (check_push_refs(local_refs, refspec_nr, refspec) < 0)
 			return -1;
 
-		remote_refs = transport->vtable->get_refs_list(transport, 1, NULL);
+		tmp_rs = parse_push_refspec(refspec_nr, refspec);
+		for (i = 0; i < refspec_nr; i++) {
+			const char *prefix = NULL;
+
+			if (tmp_rs[i].dst)
+				prefix = tmp_rs[i].dst;
+			else if (tmp_rs[i].src && !tmp_rs[i].exact_sha1)
+				prefix = tmp_rs[i].src;
+
+			if (prefix) {
+				const char *glob = strchr(prefix, '*');
+				if (glob)
+					argv_array_pushf(&ref_prefixes, "%.*s",
+							 (int)(glob - prefix),
+							 prefix);
+				else
+					expand_ref_prefix(&ref_prefixes, prefix);
+			}
+		}
+
+		remote_refs = transport->vtable->get_refs_list(transport, 1,
+							       &ref_prefixes);
+
+		argv_array_clear(&ref_prefixes);
+		free_refspec(refspec_nr, tmp_rs);
 
 		if (flags & TRANSPORT_PUSH_ALL)
 			match_flags |= MATCH_REFS_ALL;