If a configuration file contains invalid or otherwise unparseable data OpenStack services that attempt to read values from it will fail to start. While this is expected behaviour in this situation the service initialization scripts do not currently display any output indicating that there was a failure.
To work around this issue when changing configuration files restart the service as normal and then manually confirm that the service is running. For example:
# service openstack-keystone restart
Stopping keystone: [ OK ]
Starting keystone: [ OK ]
# service openstack-keystone status
keystone (pid 12632) is running...