This is actually a problem with importlib.reload() (which imp.reload() simply wraps).  The attached patch provides a test that reproduces the error.  I'll work on a fix ASAP.

Interestingly, the kind of failure depends on frozen vs. source importlib:

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ERROR: test_reload_submodule (test.test_importlib.test_api.Frozen_ReloadTests)
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Traceback (most recent call last):
  File "Lib/test/test_importlib/test_api.py", line 430, in test_reload_submodule
    self.init.reload(ham)
  File "Lib/importlib/__init__.py", line 161, in reload
    methods.exec(module)
  File "<frozen importlib._bootstrap>", line 1134, in exec
AttributeError: 'NoneType' object has no attribute 'name'

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ERROR: test_reload_submodule (test.test_importlib.test_api.Source_ReloadTests)
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Traceback (most recent call last):
  File "Lib/test/test_importlib/test_api.py", line 430, in test_reload_submodule
    self.init.reload(ham)
  File "Lib/importlib/__init__.py", line 158, in reload
    raise ImportError(msg.format(parent_name), name=parent_name)
ImportError: parent 'spam' not in sys.modules

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