Remove the old one if we found two same file handles.

Somehow sometimes the binding.watch would return a handle that was
already taken by a live handler, I have no idea of why this happened,
but we simply remove the old one for now so we do not have to throw an
exception.

src/main.coffee

@@ -40,7 +40,8 @@ class HandleWatcher extends EventEmitter
     @handle = binding.watch(@path)
     if handleWatchers.has(@handle)
       troubleWatcher = handleWatchers.get(@handle)
-      throw new Error("The handle(#{@handle}) returned by watching #{@path} is the same with an already watched path(#{troubleWatcher.path})")
+      troubleWatcher.close()
+      console.error("The handle(#{@handle}) returned by watching #{@path} is the same with an already watched path(#{troubleWatcher.path})")
     handleWatchers.add(@handle, this)
 
   closeIfNoListener: ->