ansible_playbook_python (#18530)

* ansible_playbook_python

fixes #18471

* fix tests

* removed dupe

lib/ansible/plugins/action/__init__.py

@@ -694,7 +694,7 @@ class ActionBase(with_metaclass(ABCMeta, object)):
                         pass
 
                 # remove some KNOWN keys
-                for hard in ['ansible_rsync_path']:
+                for hard in ['ansible_rsync_path', 'ansible_playbook_python']:
                     if hard in fact_keys:
                         remove_keys.add(hard)
 

lib/ansible/vars/__init__.py

@@ -20,6 +20,7 @@ from __future__ import (absolute_import, division, print_function)
 __metaclass__ = type
 
 import os
+import sys
 
 from collections import defaultdict, MutableMapping
 
@@ -392,6 +393,7 @@ class VariableManager:
 
         variables = dict()
         variables['playbook_dir'] = loader.get_basedir()
+        variables['ansible_playbook_python'] = sys.executable
 
         if host:
             variables['group_names'] = sorted([group.name for group in host.get_groups() if group.name != 'all'])