Some init scripts are dangerous to run while service is up

[Evan Broder]

A handful of our initscripts are dangerous to run when we have user VMs running. In particular, invirt-xen-config restarts the xend, which has been known to cause us to lose the xend.

Other possibilities include invirt-cluster-config and xvm-iscsi-config. Both of these initscripts have been changed to not restart their parent packages (cman and clvm, and open-iscsi, respectively) because they are guaranteed to cause downtime.

This is a little unfortunate. It would be cool if we had a better mechanism for dealing with service restarts that would cause problems, without necessarily preventing them from happening. For whatever mechanism we come up with, we should probably incorporate it into config-init.sh so we don't have to duplicate code.

Some options include:

 - Using debconf to prompt the admin as to whether or not the service should be restarted, probably defaulting to "no." (Note that debconf is now the only Debian Policy-approved way to collect input from the user when a package is installing)

 - Never restarting the service, but printing a warning message out to the user saying that they might want to do so.