B031 false positive when reassigning the returned generator

[tomasr8]

Code to reproduce:

from itertools import groupby

for _, gen in groupby([]):
    gen = list(gen)
    print(gen)

This wrongly triggers B031 even though the generator is indeed saved to a list as suggested
in the error message. You can make the error go away by assigning to a new variable so
maybe not worth it to track reassignments?