Disable hacking rule H305

This commit disables the H305 rule because it is inconsistent between
python releases. Additionally while the logical grouping is a good
thing in most cases it can be excessive to enforce sometimes. Having
reviewers attempt to catch it in most cases should be sufficient.

Change-Id: I7530fe2295c4260a20f8cdd1f853611a9a6b2f99
diff --git a/tox.ini b/tox.ini
index b3d4397..edcb901 100644
--- a/tox.ini
+++ b/tox.ini
@@ -111,7 +111,8 @@
 # H402 skipped because some docstrings aren't sentences
 # E123 skipped because it is ignored by default in the default pep8
 # E129 skipped because it is too limiting when combined with other rules
+# H305 skipped because it is inconsistent between python versions
 # Skipped because of new hacking 0.9: H405,H904
-ignore = E125,H402,E123,E129,H404,H405,H904
+ignore = E125,H402,E123,E129,H404,H405,H904,H305
 show-source = True
 exclude = .git,.venv,.tox,dist,doc,openstack,*egg