Generated signal is not unique

[enkessler]

The wait/signal usage pattern described in the Readme says that "signal puts the specified token back on the semaphore, or generates a unique new token and puts that back if none is passed". Looking at the signal method, however, it looks like it will never generate a new token. It will either use the provided token or use 1 as the token.

def signal(token = 1)
  token ||= generate_unique_token

  # other stuff
end