False positive: F401 'foo' imported but unused; when marking variable as global variable in a function

[Horstage]

False positive: F401 'foo' imported but unused

a.py:

from b import foo

def test():
    global foo
    print(foo)
    foo = 'bar'
    print(foo)

test()

b.py:

foo = 'foo'

Also resolves this PyCharm Error

[seeeturtle]

I think it may be fixed after this is merged.
because it actually regard the name as global, that is, if you rebind that name, the global one should be rebound too.