add world_size in if clause in load_from_http (#1396)

* add world_size in if clause

* add explanation

* remove LOCAL_RANK check

mmcv/runner/checkpoint.py

@@ -278,7 +278,6 @@ def load_from_http(filename, map_location=None, model_dir=None):
         dict or OrderedDict: The loaded checkpoint.
     """
     rank, world_size = get_dist_info()
-    rank = int(os.environ.get('LOCAL_RANK', rank))
     if rank == 0:
         checkpoint = load_url(
             filename, model_dir=model_dir, map_location=map_location)