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.
.. _bwcompat_module:
:mod:`cubicweb.pyramid.bwcompat`
--------------------------------
.. automodule:: cubicweb.pyramid.bwcompat
.. autofunction:: includeme
.. autoclass:: PyramidSessionHandler
:members:
.. autoclass:: CubicWebPyramidHandler
:members:
.. automethod:: __call__
.. autoclass:: TweenHandler
:members: