flake8 fixes

setup.cfg

@@ -7,4 +7,6 @@ show_source = True
 exclude = .git, __pycache__, build, dist, docs, tools, venv
 ignore =
     # required for pretty matrix formatting: multiple spaces after `,` and `[`
-    E201, E241, W504
+    E201, E241, W504,
+    # camelcase 'cPickle' imported as lowercase 'pickle'
+    N813

tests/conftest.py

@@ -75,7 +75,7 @@ class Capture(object):
         self.capfd.readouterr()
         return self
 
-    def __exit__(self, *_):
+    def __exit__(self, *args):
         self.out, self.err = self.capfd.readouterr()
 
     def __eq__(self, other):