libvirt: ignore NOSTATE in resume_state_on_host_boot() method.

Occasionally, libvirt would get NOSTATE from hypervisor as instance
state. Thus if we don't ignore instances in NOSTATE in
resume_state_on_host_boot() method, we would mistakenly reboot such
instances when we restart nova-compute service or on host boot. This
patch fixes this by adding NOSTATE into ignored_states.

Bug 1176897

Change-Id: I651cb043d7f97fde29b2a62e6ead8222062f01f7

nova/virt/libvirt/driver.py

@@ -1434,6 +1434,7 @@ def resume_state_on_host_boot(self, context, instance, network_info,
 
             ignored_states = (power_state.RUNNING,
                               power_state.SUSPENDED,
+                              power_state.NOSTATE,
                               power_state.PAUSED)
 
             if state in ignored_states: