08a7ca3747
Motivation: Due a regression introduced by e969b6917c848c83f02617386f0f73d8f0e130a2 we missed to pass the original ChannelPromise to the next ChannelOutboundHandler and so may never notify the origin ChannelPromise. This is related to #4805. Modifications: - Correctly pass the ChannelPromise - Add unit test. Result: Correctly pass the ChannelPromise on deregister(...)