Merge branch 'ds/decorate-filter-tweak'

The namespaces used by "log --decorate" from "refs/" hierarchy by
default has been tightened.

* ds/decorate-filter-tweak:
  fetch: use ref_namespaces during prefetch
  maintenance: stop writing log.excludeDecoration
  log: create log.initialDecorationSet=all
  log: add --clear-decorations option
  log: add default decoration filter
  log-tree: use ref_namespaces instead of if/else-if
  refs: use ref_namespaces for replace refs base
  refs: add array of ref namespaces
  t4207: test coloring of grafted decorations
  t4207: modernize test
  refs: allow "HEAD" as decoration filter

builtin/gc.c

@@ -910,12 +910,6 @@ static int fetch_remote(struct remote *remote, void *cbdata)
 
 static int maintenance_task_prefetch(struct maintenance_run_opts *opts)
 {
-	git_config_set_multivar_gently("log.excludedecoration",
-					"refs/prefetch/",
-					"refs/prefetch/",
-					CONFIG_FLAGS_FIXED_VALUE |
-					CONFIG_FLAGS_MULTI_REPLACE);
-
 	if (for_each_remote(fetch_remote, opts)) {
 		error(_("failed to prefetch remotes"));
 		return 1;