vzlist exit code 1 if no VMs are running

Using vzlist from vzctl-3.0.30.2-1.x86_64 whenever I'm trying to get a list of running machines, and there are none, the exit of vzlist is != 0, i.e. 1. This screws up a bit the logic of some monitoring programs, as they report that as a error condition. Is it? I mean, at least in my view it's a totally normal situation, when there are no VMs running.

For example, libvirt's python wrapper (0.9x) raises an error because of that - when asking for connection.listDomainsID and all VMs are suspended -- which is really unpleasant as a lot of hacks are needed to go around that.