Add a reset nodes function

Instead of using the retry subflow function to reset all
nodes, create a reset nodes function that will reset the
state of a given iterator of nodes to PENDING and then change
there desired intention to a provided intention.

Change-Id: Ia3f4fd4537e30a88d0d7b2271ca5be54832f724d

taskflow/engines/action_engine/graph_action.py

@@ -215,19 +215,19 @@ class FutureGraphAction(object):
                 next_nodes.add(node)
         return next_nodes
 
-    def reset_all(self):
-        self._retry_subflow(None)
-
-    def _retry_subflow(self, retry):
-        if retry is not None:
-            self._storage.set_atom_intention(retry.name, st.EXECUTE)
-            nodes_iter = self._analyzer.iterate_subgraph(retry)
-        else:
-            nodes_iter = self._analyzer.iterate_all_nodes()
-
+    def _reset_nodes(self, nodes_iter, intention=st.EXECUTE):
         for node in nodes_iter:
             if isinstance(node, task.BaseTask):
                 self._task_action.change_state(node, st.PENDING, progress=0.0)
-            else:
+            elif isinstance(node, r.Retry):
                 self._retry_action.change_state(node, st.PENDING)
-            self._storage.set_atom_intention(node.name, st.EXECUTE)
+            else:
+                raise TypeError("Unknown how to reset node %s" % node)
+            self._storage.set_atom_intention(node.name, intention)
+
+    def reset_all(self):
+        self._reset_nodes(self._analyzer.iterate_all_nodes())
+
+    def _retry_subflow(self, retry):
+        self._storage.set_atom_intention(retry.name, st.EXECUTE)
+        self._reset_nodes(self._analyzer.iterate_subgraph(retry))