Sqlalchemy event unregistering failure in UTs

When running most of the UTs, log statements like the following:

"
No sqlalchemy event for resource router found
"

are being seen during the UT teardown stage. In the case of the
py27 gate job it inundates the log and makes it difficult to
find more relevant information.

The log warnings are seen because the unregistering of events is
attempted twice, and the warning is shown on the second instance.
The unregsitering is triggered from the Neutron UT framework and
there doesn't seem to be much control over this from GBP.

This patch selectively suppresses these messages when running UTs,
and the suppressing behavior is limited to the class and method
where its considered redundant.

Change-Id: I19e83d67b93cfeaa066ef8bd586df8662778dee3

gbpservice/neutron/tests/unit/__init__.py

@@ -12,6 +12,7 @@
 from neutron._i18n import _LI
 from neutron.agent import securitygroups_rpc
 from neutron.api import extensions
+from neutron.quota import resource
 from neutron.quota import resource_registry
 from neutron.scheduler import l3_agent_scheduler
 from stevedore import named
@@ -31,3 +32,22 @@ l3_agent_scheduler.LOG.warning = l3_agent_scheduler.LOG.info
 securitygroups_rpc.LOG.warning = securitygroups_rpc.LOG.info
 local_api.LOG.warning = local_api.LOG.info
 named.LOG.warning = named.LOG.info
+
+
+import sys
+orig_warning = resource.LOG.warning
+
+
+def warning(*args):
+    try:
+        for val in sys._getframe(1).f_locals.itervalues():
+            if isinstance(val, resource.TrackedResource) and (
+                sys._getframe(1).f_code.co_name == (
+                    'unregister_events')):
+                return
+    except Exception:
+        pass
+    orig_warning(*args)
+
+
+resource.LOG.warning = warning