Fix pickling errors with cache plugins (v2)

Fixes #10945

lib/ansible/plugins/cache/base.py

@@ -26,6 +26,9 @@ from six import add_metaclass
 @add_metaclass(ABCMeta)
 class BaseCacheModule:
 
+    def __init__(self):
+        self.__getstate__ = self.copy
+
     @abstractmethod
     def get(self, key):
         pass
@@ -53,3 +56,4 @@ class BaseCacheModule:
     @abstractmethod
     def copy(self):
         pass
+