Monkey patch original current_thread _active
Monkey patch original current_thread _active

Monkey patch the original current_thread to use the up-to-date _active
global variable. This solution is based on that documented at:
https://github.com/eventlet/eventlet/issues/592

Change-Id: I49bfd9673abc7602b27dc48b8b490daaded2882c
Closes-Bug: #1863021

mahak/neutron,openstack/neutron,openstack/neutron,mahak/neutron,openstack/neutron,mahak/neutron