fetch: refactor the population of peer ref OIDs

Populate peer ref OIDs in get_ref_map instead of do_fetch. Besides
tightening scopes of variables in the code, this also prepares for
get_ref_map being able to be called multiple times within do_fetch.

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

builtin/fetch.c

@@ -351,6 +351,7 @@ static struct ref *get_ref_map(struct transport *transport,
 	/* opportunistically-updated references: */
 	struct ref *orefs = NULL, **oref_tail = &orefs;
 
+	struct string_list existing_refs = STRING_LIST_INIT_DUP;
 	const struct ref *remote_refs;
 
 	if (rs->nr)
@@ -458,7 +459,23 @@ static struct ref *get_ref_map(struct transport *transport,
 		tail = &rm->next;
 	}
 
-	return ref_remove_duplicates(ref_map);
+	ref_map = ref_remove_duplicates(ref_map);
+
+	for_each_ref(add_existing, &existing_refs);
+	for (rm = ref_map; rm; rm = rm->next) {
+		if (rm->peer_ref) {
+			struct string_list_item *peer_item =
+				string_list_lookup(&existing_refs,
+						   rm->peer_ref->name);
+			if (peer_item) {
+				struct object_id *old_oid = peer_item->util;
+				oidcpy(&rm->peer_ref->old_oid, old_oid);
+			}
+		}
+	}
+	string_list_clear(&existing_refs, 1);
+
+	return ref_map;
 }
 
 #define STORE_REF_ERROR_OTHER 1
@@ -1110,14 +1127,10 @@ static void backfill_tags(struct transport *transport, struct ref *ref_map)
 static int do_fetch(struct transport *transport,
 		    struct refspec *rs)
 {
-	struct string_list existing_refs = STRING_LIST_INIT_DUP;
 	struct ref *ref_map;
-	struct ref *rm;
 	int autotags = (transport->remote->fetch_tags == 1);
 	int retcode = 0;
 
-	for_each_ref(add_existing, &existing_refs);
-
 	if (tags == TAGS_DEFAULT) {
 		if (transport->remote->fetch_tags == 2)
 			tags = TAGS_SET;
@@ -1136,18 +1149,6 @@ static int do_fetch(struct transport *transport,
 	if (!update_head_ok)
 		check_not_current_branch(ref_map);
 
-	for (rm = ref_map; rm; rm = rm->next) {
-		if (rm->peer_ref) {
-			struct string_list_item *peer_item =
-				string_list_lookup(&existing_refs,
-						   rm->peer_ref->name);
-			if (peer_item) {
-				struct object_id *old_oid = peer_item->util;
-				oidcpy(&rm->peer_ref->old_oid, old_oid);
-			}
-		}
-	}
-
 	if (tags == TAGS_DEFAULT && autotags)
 		transport_set_option(transport, TRANS_OPT_FOLLOWTAGS, "1");
 	if (prune) {
@@ -1183,7 +1184,6 @@ static int do_fetch(struct transport *transport,
 	}
 
  cleanup:
-	string_list_clear(&existing_refs, 1);
 	return retcode;
 }