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: Ibe19ac61334d8708e3b8240e714ff98471b58111

gear/__init__.py

@@ -760,7 +760,7 @@ class BaseClientServer(object):
             self.connections_condition.release()
             try:
                 self._pollLoop()
-            except socket.error, e:
+            except socket.error as e:
                 if e.errno == errno.ECONNRESET:
                     self.log.debug("Connection reset by peer")
                     # This will get logged later at info level as
@@ -2503,7 +2503,7 @@ class Server(BaseClientServer):
             else:
                 request.connection.sendRaw(b'ERR UNKNOWN_ACL_VERB\n')
                 return
-        except ACLError, e:
+        except ACLError as e:
             self.log.info("Error in grant command: %s" % (e.message,))
             request.connection.sendRaw(b'ERR UNABLE %s\n' % (e.message,))
             return
@@ -2537,7 +2537,7 @@ class Server(BaseClientServer):
             else:
                 request.connection.sendRaw(b'ERR UNKNOWN_ACL_VERB\n')
                 return
-        except ACLError, e:
+        except ACLError as e:
             self.log.info("Error in revoke command: %s" % (e.message,))
             request.connection.sendRaw(b'ERR UNABLE %s\n' % (e.message,))
             return
@@ -2567,7 +2567,7 @@ class Server(BaseClientServer):
             else:
                 request.connection.sendRaw(b'ERR UNKNOWN_ACL_VERB\n')
                 return
-        except ACLError, e:
+        except ACLError as e:
             self.log.info("Error in self-revoke command: %s" % (e.message,))
             request.connection.sendRaw(b'ERR UNABLE %s\n' % (e.message,))
             return

gear/acl.py

@@ -95,7 +95,7 @@ class ACLEntry(object):
         if register:
             try:
                 self._register = re.compile(register)
-            except re.error, e:
+            except re.error as e:
                 raise ACLError('Regular expression error: %s' % (e.message,))
         else:
             self._register = None
@@ -110,7 +110,7 @@ class ACLEntry(object):
         if invoke:
             try:
                 self._invoke = re.compile(invoke)
-            except re.error, e:
+            except re.error as e:
                 raise ACLError('Regular expression error: %s' % (e.message,))
         else:
             self._invoke = None

tox.ini

@@ -32,6 +32,7 @@ exclude = .venv,.tox,dist,doc,*.egg
 show-source = true
 # E123, E125, and H ignored intentionally in this code-base
 ignore = E123,E125,H
+select = H231
 
 [testenv:doc]
 commands = python setup.py build_sphinx