When eventlet.wsgi closes an ECAppIter on client disconnect we need to
make sure our sub-iterators are also closed. We already kill the
backend sockets, but the executing contexts are left running until
they timeout. A slow client can result in needlessly holding queued
backend fragments until the client_timeout (default 60s).
Update associated test that exposed the problem to demonstrate the
issue more quickly.
Change-Id: Ibbc89449e7878fc4215e47e3f7dfe4ae58a2d638
7402d7d9cf