This is all my doing.

Originally the conditional was "if not timeout", about 3 months or so ago a clumsy merge of some monkey patches I collected in various libvirt deployments should have changed it to "if timeout < 0" - and i utterly failed.

-1 has a special meaning - -1 is when a slave is spawned by a latent slave but not automatically reaped. I used to use this to spin up VM's for people to poke at. In my instance I had a web form that would call stop_instance when a human asked.