`fused_step` may miss `init_post_optimizer_step_hook`

[Al]

bagua/bagua/torch_api/distributed.py

Lines 524 to 527 in 5add7f8

 # TODO: `fused_step` may miss `init_post_optimizer_step_hook` 
 def new_step_factory(optimizer): 
     def new_step(self, *args, **kwargs): 
         result = self._bagua_original_step(*args, **kwargs) 

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This issue was generated by todo based on a TODO comment in 5add7f8 when #207 was merged. cc @BaguaSys.