don't ignore rules that are already enforced

H302 / H304 are clean in the neutron source tree, so it seems
like they shouldn't be ignored. This requires no code changes to
enable.

If there is a longer standing reason for these ignores, would be
great to document in tox.ini.

Change-Id: Ib0f483e4f8fbd328815775a2a6f58be448172bd9

Author: sdague

tox.ini

@@ -52,16 +52,14 @@ commands = {posargs}
 # F812 list comprehension redefines name from line
 # H104 file contains nothing but comments
 # H237 module is removed in Python 3
-# H302 import only modules
-# H304 no relative imports
 # H305 imports not grouped correctly
 # H307 like imports should be grouped together
 # H401 docstring should not start with a space
 # H402 one line docstring needs punctuation
 # H405 multi line docstring summary not separated with an empty line
 # H904 Wrap long lines in parentheses instead of a backslash
 # TODO(marun) H404 multi line docstring should start with a summary
-ignore = E125,E126,E128,E129,E251,E265,E713,F402,F811,F812,H104,H237,H302,H304,H305,H307,H401,H402,H404,H405,H904
+ignore = E125,E126,E128,E129,E251,E265,E713,F402,F811,F812,H104,H237,H305,H307,H401,H402,H404,H405,H904
 show-source = true
 builtins = _
 exclude = .venv,.git,.tox,dist,doc,*openstack/common*,*lib/python*,*egg,build,tools,.ropeproject