Remove 'is_valid_event' method

This method is no longer needed as ironic now has
access to the automaton provided 'is_actionable_event'
method that provides an equivalent api.

Change-Id: Ib0edd2da7e36b91c3fba306133f011db5a87019f

ironic/api/controllers/v1/node.py

@@ -402,7 +402,7 @@ class NodeStatesController(rest.RestController):
 
         m = ir_states.machine.copy()
         m.initialize(rpc_node.provision_state)
-        if not m.is_valid_event(ir_states.VERBS.get(target, target)):
+        if not m.is_actionable_event(ir_states.VERBS.get(target, target)):
             # Normally, we let the task manager recognize and deal with
             # NodeLocked exceptions. However, that isn't done until the RPC
             # calls below.

ironic/common/fsm.py

@@ -104,19 +104,6 @@ class FSM(machines.FiniteMachine):
         if self._states[self._current.name]['target'] is not None:
             self._target_state = self._states[self._current.name]['target']
 
-    def is_valid_event(self, event):
-        """Check whether the event is actionable in the current state."""
-        # TODO(harlowja): remove this when
-        # https://review.openstack.org/191955 merges and is made available.
-        current = self._current
-        if current is None:
-            return False
-        if self._states[current.name]['terminal']:
-            return False
-        if event not in self._transitions[current.name]:
-            return False
-        return True
-
     @_translate_excp
     def initialize(self, start_state=None):
         super(FSM, self).initialize(start_state=start_state)