Fix stable/stein builds

Python2.7 is only available on the bionic nodesets.

Change-Id: I07206a1640b5e744f95a37d250a60ee6b4d23e53

gbpclient/gbpshell.py

@@ -675,7 +675,6 @@ class GBPShell(app.App):
         subcommand = self.command_manager.find_command(argv)
         cmd_factory, cmd_name, sub_argv = subcommand
         cmd = cmd_factory(self, self.options)
-        err = None
         result = 1
         try:
             self.prepare_to_run_command(cmd)

tox.ini

@@ -17,7 +17,7 @@ deps =
 commands = stestr run {posargs}
 
 [testenv:pep8]
-basepython = python2.7
+basepython = python3
 commands =
   flake8
   {[testenv:bandit]commands}
@@ -56,6 +56,6 @@ commands = bandit -r {toxinidir}/gbpclient -x {toxinidir}/gbpclient/tests -n5 -s
 #
 # REVISIT: Fix code and remove E129,E251,H305,H307,H405,H904 added for
 # hacking 0.9.2
-ignore = E125,H302,E129,E251,F601,H305,H307,H405,H904,W503,W504,W605
+ignore = E125,H302,E129,E251,F601,H216,H305,H307,H405,H904,W503,W504,W605
 show-source = true
 exclude=.venv,.git,.tox,dist,doc,*openstack/common*,*lib/python*,*egg,tools