Properly look for parent become attribute

Corrects inheritence of the boolean value, which needs some special
consideration from other (string/int) values.

Fixes #13872

lib/ansible/playbook/become.py

@@ -106,10 +106,11 @@ class Become:
         '''
         Override for the 'become' getattr fetcher, used from Base.
         '''
+        value = self._attributes['become']
         if hasattr(self, '_get_parent_attribute'):
-            return self._get_parent_attribute('become')
-        else:
-            return self._attributes['become']
+            if self._get_parent_attribute('become'):
+                return True
+        return value
 
     def _get_attr_become_method(self):
         '''

lib/ansible/playbook/task.py

@@ -417,7 +417,7 @@ class Task(Base, Conditional, Taggable, Become):
 
     def _get_attr_any_errors_fatal(self):
         '''
-        Override for the 'tags' getattr fetcher, used from Base.
+        Override for the 'any_errors_fatal' getattr fetcher, used from Base.
         '''
         any_errors_fatal = self._attributes['any_errors_fatal']
         if hasattr(self, '_get_parent_attribute'):