HTTPCORE-336: Unhandled CancelledKeyException leads to a shutdown of the underlying IOReactor
Contributed by Thomas Dudek <mail.dudek at gmail.com>

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpcore/branches/4.2.x@1463609 13f79535-47bb-0310-9956-ffa450edef68