nbdev_test having issues because of Python caching modules

[loayshaqir1]

No need to add example as the explanation of the issue is simple.
nbdev_test uses up to 8 workers (threads) to run the tests, if we have a library called new_lib for example that its __init__ file has some global variables in it, if we have more than 8 tests, there will be a worker that will run more than one test, and because all the tests do import new_lib, that worker that runs more than one test won't import new_lib again and give the new test a fresh new environment as new_lib is already in sys.modules so because of Python caching modules it won't be imported again.
you should do something that refreshes workers before assigning them new tests