fix cache 'update' method to be 'mapping' compatible

- also simplify the update functions
 - fix methods and allwow backwards compat with plugins overriding 'update'

changelogs/fragments/vm_fix.yml

@@ -0,0 +1,2 @@
+bugfixes:
+    - fix issue with incorrect dict update in vars manager

lib/ansible/plugins/cache/__init__.py

@@ -292,10 +292,18 @@ class FactCache(MutableMapping):
         """ Flush the fact cache of all keys. """
         self._plugin.flush()
 
-    def update(self, key, value):
+    def update(self, host_facts):
+        """ We override the normal update to ensure we always use the 'setter' method """
+        for key in host_facts:
+            try:
                 host_cache = self._plugin.get(key)
-        host_cache.update(value)
+                if host_cache:
+                    host_cache.update(host_facts[key])
+                else:
+                    host_cache = host_facts[key]
                 self._plugin.set(key, host_cache)
+            except KeyError:
+                self._plugin.set(key, host_facts[key])
 
 
 class InventoryFileCacheModule(BaseFileCacheModule):
@@ -314,7 +322,7 @@ class InventoryFileCacheModule(BaseFileCacheModule):
     def validate_cache_connection(self):
         try:
             super(InventoryFileCacheModule, self).validate_cache_connection()
-        except AnsibleError as e:
+        except AnsibleError:
             cache_connection_set = False
         else:
             cache_connection_set = True

lib/ansible/vars/manager.py

@@ -625,8 +625,7 @@ class VariableManager:
         '''
         Clears the facts for a host
         '''
-        if hostname in self._fact_cache:
-            del self._fact_cache[hostname]
+        self._fact_cache.pop(hostname, None)
 
     def set_host_facts(self, host, facts):
         '''
@@ -636,11 +635,14 @@ class VariableManager:
         if not isinstance(facts, dict):
             raise AnsibleAssertionError("the type of 'facts' to set for host_facts should be a dict but is a %s" % type(facts))
 
-        if host.name not in self._fact_cache:
-            self._fact_cache[host.name] = facts
-        else:
         try:
+            try:
+                # this is a cache plugin, not a dictionary
+                self._fact_cache.update({host.name: facts})
+            except TypeError:
+                # this is here for backwards compatibilty for the time cache plugins were not 'dict compatible'
                 self._fact_cache.update(host.name, facts)
+                display.deprecated("Your configured fact cache plugin is using a deprecated form of the 'update' method", version="2.12")
         except KeyError:
             self._fact_cache[host.name] = facts
 
@@ -652,9 +654,6 @@ class VariableManager:
         if not isinstance(facts, dict):
             raise AnsibleAssertionError("the type of 'facts' to set for nonpersistent_facts should be a dict but is a %s" % type(facts))
 
-        if host.name not in self._nonpersistent_fact_cache:
-            self._nonpersistent_fact_cache[host.name] = facts
-        else:
         try:
             self._nonpersistent_fact_cache[host.name].update(facts)
         except KeyError: