Fixed #18013 -- Use the new 'as' syntax for exceptions.

Thanks Clueless for the initial patch.
Note that unittest has been purposely left out (external package only used by Python 2.6).

django/test/testcases.py

@@ -84,7 +84,7 @@ def restore_transaction_methods():
 def assert_and_parse_html(self, html, user_msg, msg):
     try:
         dom = parse_html(html)
-    except HTMLParseError, e:
+    except HTMLParseError as e:
         standardMsg = u'%s\n%s' % (msg, e.msg)
         self.fail(self._formatMessage(user_msg, standardMsg))
     return dom
@@ -1035,7 +1035,7 @@ class LiveServerThread(threading.Thread):
                 try:
                     self.httpd = StoppableWSGIServer(
                         (self.host, port), QuietWSGIRequestHandler)
-                except WSGIServerException, e:
+                except WSGIServerException as e:
                     if (index + 1 < len(self.possible_ports) and
                         e.args[0].errno == errno.EADDRINUSE):
                         # This port is already in use, so we go on and try with
@@ -1054,7 +1054,7 @@ class LiveServerThread(threading.Thread):
             self.httpd.set_app(handler)
             self.is_ready.set()
             self.httpd.serve_forever()
-        except Exception, e:
+        except Exception as e:
             self.error = e
             self.is_ready.set()