Handle ResponseError when CLIENT command is not supported (#1514)

* catch redis ResponseError if CLIENT command not supported

* use Warning instead of UserWarning

rq/worker.py

@@ -221,7 +221,15 @@ class Worker:
         if prepare_for_work:
             self.hostname = socket.gethostname()
             self.pid = os.getpid()
+            try:
                 connection.client_setname(self.name)
+            except redis.exceptions.ResponseError:
+                warnings.warn(
+                    'CLIENT command not supported, setting ip_address to unknown',
+                    Warning
+                )
+                self.ip_address = 'unknown'
+            else:
                 self.ip_address = [client['addr'] for client in connection.client_list() if client['name'] == self.name][0]
         else:
             self.hostname = None