Catch exception on stop action.

Therefore do not block next stop actions.

ccnode/hypervisor/__init__.py

@@ -125,10 +125,14 @@ class Handler(HostHandler):
     def vm_stop(self, vm_names=None, force=False):
         logger.debug('VM stop')
         for vm in self.iter_vms(vm_names):
-            if force:
-                vm.destroy()
-            else:
-                vm.stop()
+            try:
+                if force:
+                    vm.destroy()
+                else:
+                    vm.stop()
+            except libvirt.libvirtError:
+                # should we return errors ?
+                pass
 
     def vm_start(self, vm_names=None):
         logger.debug('VM start')