Fix errors found by new pycodestyle

pycodestyle 2.6.0 has some new errors, fix them.

Also bumped minimum hacking to 3.0.1 so it pulls in
the correct flake8, etc, libraries.

Added basepython directive in tox.ini since local
'tox -e pep8' runs were using python2 otherwise.

Change-Id: I3a9f7c2df5b68a3bad036121c9b10b1c184d261c

neutron_lib/utils/helpers.py

@@ -128,8 +128,8 @@ def diff_list_of_dict(old_list, new_list):
     :returns: A tuple where the first item is a list of the added dicts in
         the diff and the second item is the removed dicts.
     """
-    new_set = set([dict2str(l) for l in new_list])
-    old_set = set([dict2str(l) for l in old_list])
+    new_set = set([dict2str(i) for i in new_list])
+    old_set = set([dict2str(i) for i in old_list])
     added = new_set - old_set
     removed = old_set - new_set
     return [str2dict(a) for a in added], [str2dict(r) for r in removed]

test-requirements.txt

@@ -2,7 +2,7 @@
 # of appearance. Changing the order has an impact on the overall integration
 # process, which may cause wedges in the gate later.
 
-hacking>=3.0.0,<3.1 # Apache-2.0
+hacking>=3.0.1,<3.1.0 # Apache-2.0
 
 bandit!=1.6.0,>=1.1.0 # Apache-2.0
 coverage!=4.4,>=4.0 # Apache-2.0

tox.ini

@@ -5,6 +5,7 @@ skipsdist = True
 ignore_basepython_conflict = True
 
 [testenv]
+basepython = python3
 usedevelop = True
 passenv = TRACE_FAILONLY
 setenv =