Comment 27 for bug 1184041

This has a side affect of breaking security group linking via source groups.

Example:

Secgroup "Server" has rule

+-------------+-----------+---------+----------+---------------+
| IP Protocol | From Port | To Port | IP Range | Source Group |
+-------------+-----------+---------+----------+---------------+
| tcp | 8140 | 8140 | | client |
+-------------+-----------+---------+----------+---------------+

Instance A is running and is associated with the "Server" secgroup

Now if a create a new instance with the "client" security group it should add a rule to instance A to all the new instance to talk to it.

This no longer gets added as it uses the cached version.

Restarting nova-compute will fix this and the rule will be applied.