Two fixes to action plugins

* Fix the task_vars parameter to not default to a mutable type (dict)
* Implement invocation in the base class's run() method have each action
  module call the run() method's implemention in the base class.
* Return values from the action plugins' run() method takes the return
  value from the base class run() method into account so that invocation
  makes its way to the output.

Fixes #12869

lib/ansible/plugins/action/debug.py

@@ -20,27 +20,32 @@ __metaclass__ = type
 from ansible.plugins.action import ActionBase
 from ansible.utils.boolean import boolean
 
+
 class ActionModule(ActionBase):
     ''' Print statements during execution '''
 
     TRANSFERS_FILES = False
 
-    def run(self, tmp=None, task_vars=dict()):
+    def run(self, tmp=None, task_vars=None):
+        if task_vars is None:
+            task_vars = dict()
+
+        result = super(ActionModule, self).run(tmp, task_vars)
 
         if 'msg' in self._task.args:
             if 'fail' in self._task.args and boolean(self._task.args['fail']):
-                result = dict(failed=True, msg=self._task.args['msg'])
+                result['failed'] = True
+                result['msg'] = self._task.args['msg']
             else:
-                result = dict(msg=self._task.args['msg'])
+                result['msg'] = self._task.args['msg']
         # FIXME: move the LOOKUP_REGEX somewhere else
         elif 'var' in self._task.args: # and not utils.LOOKUP_REGEX.search(self._task.args['var']):
             results = self._templar.template(self._task.args['var'], convert_bare=True)
             if results == self._task.args['var']:
                 results = "VARIABLE IS NOT DEFINED!"
-            result = dict()
             result[self._task.args['var']] = results
         else:
-            result = dict(msg='here we are')
+            result['msg'] = 'here we are'
 
         # force flag to make debug output module always verbose
         result['_ansible_verbose_always'] = True