Ask for forward thread to end after VNC process is dead

cccli/commands/vnc.py

@@ -58,6 +58,7 @@ class VNCViewer(threading.Thread):
                                 shell=True, close_fds=True,
                                 stdin=onull, stdout=onull, stderr=onull)
         proc.wait()
+        fwd.stop()
         del self.cli.forwards[fwd.id]
 
 class Command_vnc(TqlCommand):