Poison entries outside of main lock
Poisoning entries may involve reaction from their callbacks, which
can attempt to circle back through connections.
Make sure we poison them outside of lock context, so that any
callbacks end up seeing a poisoned connection, but without the lock
being held -- hence the locks can be acquired in-order.
JIRA: CONTROLLER-1893
Change-Id: I26551d052307812e76f3e45024a77dbb83312b17
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>
(cherry picked from commit
e983d61d93fe2da50f9c4112fa28c7fe4ee5ffef)