Comment 2 for bug 1560242

Session (0x7f286096a030) on which the Read Event triggered as part of io::ReaderTask is not the same session that the xmpp state-machine is pointing to (0x7f28608169a0) as part of xmpp::StateMachine task.

This indicates a close was received on older session (0x7f286096a030) and processed as part of xmpp::StateMachine task and new session (0x7f28608169a0) is created, while we were in the middle of receiving data on the session (0x7f286096a030), hence the two tasks need to be made exclusive, i.e processsing on data and processing of close need to be exclusive.