Comment 13 for bug 510658

Dustin's right on 'a'. Can't catch -9 and if libvirtd dies for some reason, its pid file is left around.

However, Loic is right about 'c' because of qemu:///session (I forgot about this when we discussed this initially). Since the upstart job is only for qemu:///system, and only the libvirtd for qemu:///system writes a pid file to /var/run, and upstart is smart about not starting things it's already started (is this true of 'pre-start'?), we can probably just forget the 'pidof' check and simply remove the pid file unconditionally. A comment in the job might be in order though, since the resulting snippet looks really weird:

pre-start script
        mkdir -p /var/run/libvirt
        rm -f /var/run/libvirtd.pid
        ...