Fixing new caching related issue with host vars

The vars_cache was not being properly merged with the setup_cache
for all hosts, which was previously not noticed when registered
variables were stored in the setup_cache.

Fixes #8944

lib/ansible/cache/base.py

@@ -36,3 +36,6 @@ class BaseCacheModule(object):
 
     def flush(self):
         raise exceptions.NotImplementedError
+
+    def copy(self):
+        raise exceptions.NotImplementedError

lib/ansible/cache/memcached.py

@@ -186,3 +186,6 @@ class CacheModule(BaseCacheModule):
     def flush(self):
         for key in self.keys():
             self.delete(key)
+
+    def copy(self):
+        return self._keys.copy()

lib/ansible/cache/memory.py

@@ -15,7 +15,9 @@
 # You should have received a copy of the GNU General Public License
 # along with Ansible.  If not, see <http://www.gnu.org/licenses/>.
 
-class CacheModule(object):
+from ansible.cache.base import BaseCacheModule
+
+class CacheModule(BaseCacheModule):
 
     def __init__(self, *args, **kwargs):
         self._cache = {}
@@ -37,3 +39,6 @@ class CacheModule(object):
 
     def flush(self):
         self._cache = {}
+
+    def copy(self):
+        return self._cache.copy()

lib/ansible/cache/redis.py

@@ -93,3 +93,10 @@ class CacheModule(BaseCacheModule):
     def flush(self):
         for key in self.keys():
             self.delete(key)
+
+    def copy(self):
+        # FIXME: there is probably a better way to do this in redis
+        ret = dict()
+        for key in self.keys():
+            ret[key] self.get(key)
+        return ret

lib/ansible/runner/__init__.py

@@ -598,7 +598,7 @@ class Runner(object):
 
         # merge the VARS and SETUP caches for this host
         combined_cache = self.setup_cache.copy()
-        combined_cache.setdefault(host, {}).update(self.vars_cache.get(host, {}))
+        combined_cache.update(self.vars_cache)
 
         hostvars = HostVars(combined_cache, self.inventory, vault_password=self.vault_pass)