- This means connections become untracked sooner than before and not all blocks will
necessarily be returned.
- The assertion in the MemoryPoolBlock2 finalizer was weakened because FilteredStreamAdapter
will continue to use blocks after libuv stops tracking the associated connection.
- Make 100% sure we don't accept new connections after we dispose the listen socket by using a flag.
- Add a (currently unused) AllowStop method to KestrelThread. This is meant to be called from
listeners when we stop accepting new connections, but needs investigation to prevent flakiness.
Stephen Halter