Use except x as y instead of except x, y

According to https://docs.python.org/3/howto/pyporting.html the
syntax changed in Python 3.x. The new syntax is usable with
Python >= 2.6 and should be preferred to be compatible with Python3.

Enabled hacking check H231.

Change-Id: I4c20a04bc7732efc2d4bbcbc3d285107b244e5fa

launch/utils.py

@@ -188,7 +188,7 @@ def ssh_connect(ip, username, connect_kwargs={}, timeout=60):
         try:
             client = SSHClient(ip, username, **connect_kwargs)
             break
-        except socket.error, e:
+        except socket.error as e:
             print "While testing ssh access:", e
             time.sleep(5)
 

modules/log_processor/files/log-gearman-worker.py

@@ -180,7 +180,7 @@ class LogRetriever(threading.Thread):
         raw_buf = b''
         try:
             gzipped, raw_buf = self._get_log_data(source_url, retry)
-        except urllib2.HTTPError, e:
+        except urllib2.HTTPError as e:
             if e.code == 404:
                 logging.info("Unable to retrieve %s: HTTP error 404" %
                              source_url)

tox.ini

@@ -31,6 +31,7 @@ commands = python modules/accessbot/files/checkaccess.py -l modules/openstack_pr
 show-source = True
 exclude = .tox
 ignore = E125,H
+select = H231
 
 [testenv:jjb]
 basepython = python2.7