Fix flake8 issues since release 3.6.0
Flake8 had a new release which raise new issues, namely:
W504: line break after binary operator
F841: local variable 'ex' is assigned to but never used
W605: invalid escape sequence
F821: undefined name 'buffer' (noqa seems the only way to avoid this false positive)
Also pin flake8>=3.6 in our tests and make explicit that we use python3 to run
flake8 tests.
.. -*- coding: utf-8 -*-
Writing text reports with RestructuredText
==========================================
|cubicweb| offers several text formats for the RichString type used in schemas,
including restructuredtext.
Three additional restructuredtext roles are defined by |cubicweb|:
.. autofunction:: cubicweb.ext.rest.eid_reference_role
.. autofunction:: cubicweb.ext.rest.rql_role
.. autofunction:: cubicweb.ext.rest.bookmark_role