fix https://github.com/spesmilo/electrum/issues/2204

lib/network.py

@@ -432,6 +432,8 @@ class Network(util.DaemonThread):
         self.print_error("stopping network")
         for interface in self.interfaces.values():
             self.close_interface(interface)
+        if self.interface:
+            self.close_interface(self.interface)
         assert self.interface is None
         assert not self.interfaces
         self.connecting = set()
@@ -669,7 +671,8 @@ class Network(util.DaemonThread):
         # Responses to connection attempts?
         while not self.socket_queue.empty():
             server, socket = self.socket_queue.get()
-            self.connecting.remove(server)
+            if server in self.connecting:
+                self.connecting.remove(server)
             if socket:
                 self.new_interface(server, socket)
             else: