Merge branch 'ew/fetch-hiderefs'

A new "fetch.hideRefs" option can be used to exclude specified refs
from "rev-list --objects --stdin --not --all" traversal for
checking object connectivity, most useful when there are many
unrelated histories in a single repository.

* ew/fetch-hiderefs:
  fetch: support hideRefs to speed up connectivity checks

builtin/fetch.c

@@ -1133,6 +1133,7 @@ static int store_updated_refs(const char *raw_url, const char *remote_name,
 	if (!connectivity_checked) {
 		struct check_connected_options opt = CHECK_CONNECTED_INIT;
 
+		opt.exclude_hidden_refs_section = "fetch";
 		rm = ref_map;
 		if (check_connected(iterate_ref_map, &rm, &opt)) {
 			rc = error(_("%s did not send all necessary objects\n"), url);
@@ -1326,6 +1327,7 @@ static int check_exist_and_connected(struct ref *ref_map)
 	}
 
 	opt.quiet = 1;
+	opt.exclude_hidden_refs_section = "fetch";
 	return check_connected(iterate_ref_map, &rm, &opt);
 }