Make default var lookup for tasks follow the dep chain

Related to #14296 (@jjshoe's follow-up example on that issue)

lib/ansible/playbook/role/__init__.py

@@ -252,10 +252,13 @@ class Role(Base, Become, Conditional, Taggable):
     def get_parents(self):
         return self._parents
 
-    def get_default_vars(self):
+    def get_default_vars(self, dep_chain=[]):
         default_vars = dict()
         for dep in self.get_all_dependencies():
             default_vars = combine_vars(default_vars, dep.get_default_vars())
+        if dep_chain:
+            for parent in dep_chain:
+                default_vars = combine_vars(default_vars, parent._default_vars)
         default_vars = combine_vars(default_vars, self._default_vars)
         return default_vars
 

lib/ansible/vars/__init__.py

@@ -220,7 +220,7 @@ class VariableManager:
             # sure it sees its defaults above any other roles, as we previously
             # (v1) made sure each task had a copy of its roles default vars
             if task and task._role is not None:
-                all_vars = combine_vars(all_vars, task._role.get_default_vars())
+                all_vars = combine_vars(all_vars, task._role.get_default_vars(dep_chain=task._block._dep_chain))
 
         if host:
             # next, if a host is specified, we load any vars from group_vars