Fix flake8 errors/warnings about import in cubicweb/_exceptions.py
We either ignore errors in case of name re-exports and drop re-exports
from old backwards compatibility. We fix the only occurrence of
NoSelectableObject being imported from cubicweb in tests and update the
import to use lgc instead.
[bdist_wheel]
universal = 1
[check-manifest]
ignore =
debian
debian/*
cubicweb.spec
__pkginfo__.py