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:
eventlet/eventlet#592

Change-Id: I97c2a756076299a01170beb5bec3fa0e49593146
Story: 2007614

ironic/cmd/__init__.py

@@ -24,6 +24,12 @@
 import eventlet
 
 eventlet.monkey_patch(os=False)
+# Monkey patch the original current_thread to use the up-to-date _active
+# global variable. See https://bugs.launchpad.net/bugs/1863021 and
+# https://github.com/eventlet/eventlet/issues/592
+import __original_module_threading as orig_threading  # noqa
+import threading  # noqa
+orig_threading.current_thread.__globals__['_active'] = threading._active
 
 from ironic.common import i18n  # noqa for I202 due to 'import eventlet' above