Tweak the 9969 fix a little

If we have busy nodes and excluded nodes, then don't retry with the
excluded ones enabled.  Instead, wait for the busy ones to be nonbusy.

src/or/routerlist.c

@@ -1549,7 +1549,8 @@ router_pick_directory_server_impl(dirinfo_type_t type, int flags,
   smartlist_free(overloaded_direct);
   smartlist_free(overloaded_tunnel);
 
-  if (result == NULL && try_excluding && !options->StrictNodes && n_excluded) {
+  if (result == NULL && try_excluding && !options->StrictNodes && n_excluded
+      && !n_busy) {
     /* If we got no result, and we are excluding nodes, and StrictNodes is
      * not set, try again without excluding nodes. */
     try_excluding = 0;