azdev test core fails: AttributeError: 'AssertionRewritingHook' object has no attribute 'find_spec'

[jiasli]

Command:

azdev test core --discover --series

It fails with error:

______________________ HelpTest.test_help_loads ______________________ 

name = 'azure.mgmt.applicationinsights.models.web_test', path = ['d:\\cli\\env38\\lib\\site-packages\\azure\\mgmt\\applicationinsights\\models'], target = None

>   ???
E   AttributeError: 'AssertionRewritingHook' object has no attribute 'find_spec'

<frozen importlib._bootstrap>:908: AttributeError

This seems to be related to pytest-dev/pytest#1888.

[jiasli]

This issue only happens on Windows with pytest 4.4.2.

> pip list | sls pytest

pytest                                4.4.2
pytest-forked                         1.1.3
pytest-xdist                          1.31.0

It is gone after upgrading pytest to 5.4.3.

> pip list | sls pytest

pytest                                5.4.3
pytest-forked                         1.1.3
pytest-xdist                          1.31.0