[1.5.x] Fixed #19355 -- Improved LiveServerThread's handling of exceptions. Thanks to flub for the report.

Backport of 612357f8ef

django/test/testcases.py

@@ -1022,6 +1022,7 @@ class LiveServerThread(threading.Thread):
                         (self.host, port), QuietWSGIRequestHandler)
                 except WSGIServerException as e:
                     if (index + 1 < len(self.possible_ports) and
+                        hasattr(e.args[0], 'errno') and
                         e.args[0].errno == errno.EADDRINUSE):
                         # This port is already in use, so we go on and try with
                         # the next one in the list.