merge from master to features

tox.ini

@@ -40,7 +40,7 @@ skipsdist = True
 usedevelop = True
 basepython = python3.6
 deps = pre-commit
-commands = pre-commit run --all-files
+commands = pre-commit run --all-files --show-diff-on-failure
 
 [testenv:py27-xdist]
 deps =
@@ -204,9 +204,7 @@ filterwarnings =
     ignore:.*type argument to addoption.*:DeprecationWarning
     # produced by python >=3.5 on execnet (pytest-xdist)
     ignore:.*inspect.getargspec.*deprecated, use inspect.signature.*:DeprecationWarning
-    # ignore warning about package resolution using __spec__ or __package__
-    # should be a temporary solution, see #3061 for discussion
-    ignore:.*can't resolve package from __spec__ or __package__.*:ImportWarning
 
 [flake8]
 max-line-length = 120
+ignore = E203,W503