pywsgi: stop processing requests if self.socket is set to None

this is needed for websocket which needs to own the connection

--HG--
extra : transplant_source : %C2%FF%0C%9F%C0%C3h%23%18M%F9%8CL%1D%E7%29%5B%85%3B%2A

gevent/pywsgi.py

@@ -158,7 +158,7 @@ class WSGIHandler(object):
 
     def handle(self):
         try:
-            while True:
+            while self.socket is not None:
                 self.time_start = time.time()
                 self.time_finish = 0
                 result = self.handle_one_request()
@@ -173,11 +173,12 @@ class WSGIHandler(object):
                 self.log_request()
                 break
         finally:
-            try:
-                self.socket._sock.close()  # do not rely on garbage collection
-                self.socket.close()
-            except socket.error:
-                pass
+            if self.socket is not None:
+                try:
+                    self.socket._sock.close()  # do not rely on garbage collection
+                    self.socket.close()
+                except socket.error:
+                    pass
             self.__dict__.pop('socket', None)
             self.__dict__.pop('rfile', None)
             self.__dict__.pop('wfile', None)