Comment 15 for bug 1550886

In regards to discussions on whether or not to include this in stable/liberty or not: the race occurs when creating and deleting HA routers, and is especially apparent when the router is the first one a tenant has created. In this case, the resulting race can produce a wide array of effects, such as not creating all the resources and failure to schedule the router to the minimum required HA agents (even though there are more available).

This can happen very easily when running rally's create_and_delete_routers sample task and have been reported to happen on a few large deployments.

This rather-complex patch makes sure an agent is not made aware of routers which are currently ALLOCATING. As a safeguard, during specific sensitive areas of the code (and specifically when scheduling a router), its' status is modified to ALLOCATING.