Remove supefluous check.
Remove supefluous check.

fail_connection() can now be called safely multiple times in parallel,
solving the general problem, while this check only adressed an instance.

dommert/pywebsockets,andrewyoung1991/websockets,aaugustin/websockets,aaugustin/websockets,aaugustin/websockets,aaugustin/websockets,biddyweb/websockets