py3: add __pycache__ to .hgignore
Something changed with Python 3 just like million on things. Maybe they should
named Python 3 as anaconda or cobra instead of just increasing the version
number.
This makes test-custom-filters.t pass on Python 3.
Differential Revision: https://phab.mercurial-scm.org/D5039
warning
error
b'buffered\n'
colored? True
colored? True