Don't check stack staus for already migrated stacks

If stacks are already migrated to convergence, there is no point
in checking stack status before returning. This will allow re-run
of the command inspite of migrated stacks in FAILED state.

Change-Id: Ia0e34423377843adee8efc7f23d2c2df5dac8e20
Task: 40266
(cherry picked from commit 8d5d2a8fb6)
(cherry picked from commit 1f66e61ca5)

heat/engine/service.py

@@ -2293,15 +2293,15 @@ class EngineService(service.ServiceBase):
             msg = _("Migration of nested stack %s") % stack_id
             raise exception.NotSupported(feature=msg)
 
-        if parent_stack.status != parent_stack.COMPLETE:
-            raise exception.ActionNotComplete(stack_name=parent_stack.name,
-                                              action=parent_stack.action)
-
         if parent_stack.convergence:
             LOG.info("Convergence was already enabled for stack %s",
                      stack_id)
             return
 
+        if parent_stack.status != parent_stack.COMPLETE:
+            raise exception.ActionNotComplete(stack_name=parent_stack.name,
+                                              action=parent_stack.action)
+
         db_stacks = stack_object.Stack.get_all_by_root_owner_id(
             ctxt, parent_stack.id)
         stacks = [parser.Stack.load(ctxt, stack_id=st.id,