[compatibility] used backward-compatible API for global process group (#758)

colossalai/context/parallel_context.py

@@ -374,7 +374,7 @@ class ParallelContext(metaclass=SingletonMeta):
         # None will give the default global process group for pytorch dist operations
         ranks = list(range(world_size))
         cpu_group = dist.new_group(ranks, backend='gloo') if dist.get_backend() != 'gloo' else None
-        self._register_dist(rank, world_size, None, cpu_group, ranks, ParallelMode.GLOBAL)
+        self._register_dist(rank, world_size, dist.GroupMember.WORLD, cpu_group, ranks, ParallelMode.GLOBAL)
         self.add_global_rank(ParallelMode.GLOBAL, rank)
 
     def _register_dist(self, local_rank, world_size, process_group, cpu_group, ranks_in_group, mode):