ProtocolNegotiators leaks ByteBufs on failure #1401
Description
As reported by @trask in #1277 with repro repo at https://github.com/trask/grpc-netty-leak-repro. The key distinguishing feature is BufferUntilChannelActiveHandler in the log here:
SEVERE: LEAK: ByteBuf.release() was not called before it's garbage-collected. See http://netty.io/wiki/reference-counted-objects.html for more information.
Recent access records: 2
#2:
Hint: 'ProtocolNegotiators$BufferUntilChannelActiveHandler#0' will handle the message from this point.
When looking at the code, it is obvious it doesn't release when it fails the promise. This leak only happens when failing to establish a connection to the server.