Location
windows.go line 103 of ref 8fa037f (current HEAD) introduced in ceba4ef

Problem
The mutex is unlocked right after locking it. It seems like somebody forgot to put it there. Both kqueue.go and inotify.go perform a defer.

func (w *Watcher) WatchList() []string {
   w.mu.Lock()
   w.mu.Unlock()
   // ....
}

Should be

func (w *Watcher) WatchList() []string {
   w.mu.Lock()
   defer w.mu.Unlock()
   // ....
}