HTTPASYNC-68: Connection closed by the opposite endpoint immediately upon its lease from the pool is never released back and reclaimed by the pool (collection leak)
Contributed by Dmitry Potapov <potapov.d at gmail.com>

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpasyncclient/trunk@1567748 13f79535-47bb-0310-9956-ffa450edef68