With v0.9.0 I cannot instantiate DeepSpeed. I get the error "AttributeError: 'NoneType' object has no attribute 'optimizer_name'"

Describe the bug
With v0.9.0 I cannot instantiate DeepSpeed. I get the error "AttributeError: 'NoneType' object has no attribute 'optimizer_name'"

To Reproduce
Here is the code that used to work when istantiating DeepSpeed:

class Engine(DeepSpeedEngine):
def init(self, *args, **kwargs):
...
...
super().init(None, *args, **kwargs)
...
...

Expected behavior
A usable DeepSpeed instance will be created.

Actual result*
I get the following error traceback:
....
....
File "/usr/local/lib/python3.10/site-packages/deepspeed/runtime/engine.py", line 264, in init
self._do_sanity_check()
File "/usr/local/lib/python3.10/site-packages/deepspeed/runtime/engine.py", line 988, in _do_sanity_check
if self.optimizer_name() is not None:
File "/usr/local/lib/python3.10/site-packages/deepspeed/runtime/engine.py", line 648, in optimizer_name
return (self.client_optimizer.class.name if self.client_optimizer else self._config.optimizer_name)
AttributeError: 'NoneType' object has no attribute 'optimizer_name'

It seems that cfg is now mandatory during insanitation. It wasn't mandatory before.