fixes ZEN-15769: fix locking for global vhost routing handler

https://jira.zenoss.com/browse/ZEN-15769

![screen shot 2014-12-12 at 17 00 10](https://cloud.githubusercontent.com/assets/2837923/5420864/63acb7f0-8220-11e4-8ba0-4ba17cda64d1.png)