Fix undefined 'sock' Exception

Author: alexey-v-paramonov

SimpleWebSocketServer/SimpleWebSocketServer.py

@@ -639,6 +639,7 @@ def serveonce(self):
 
       for ready in rList:
          if ready == self.serversocket:
+            sock = None
             try:
                sock, address = self.serversocket.accept()
                newsock = self._decorateSocket(sock)