playframework/Play20 — pull request #685 by brikis98 (2013-01-21 07:08:55+00:00)
Title: Ensure Global.onRequestCompletion cannot be called more than once

As explained in [lighthouse-948](https://play.lighthouseapp.com/projects/82401-play-20/tickets/948-globalonrequestcompletion-can-be-called-multiple-times-per-request), ensure Global.onRequestCompletion cannot be called more than once per request.