component AP gateway: use the new priority argument of addManagedNode:

priority is needed because we'll need to inspect former items on retract to check the
Acitivy to use (it may be an `Undo` activity is some cases), and this must be done before
the cache is updated by pubsub cache plugin.

rel 370

sat/plugins/plugin_comp_ap_gateway/__init__.py

@@ -132,7 +132,12 @@ class APGateway:
         self._t = host.plugins["TEXT_SYNTAXES"]
         self._i = host.plugins["IDENTITY"]
         self._p.addManagedNode(
-            "", items_cb=self._itemsReceived
+            "",
+            items_cb=self._itemsReceived,
+            # we want to be sure that the callbacks are launched before pubsub cache's
+            # one, as we need to inspect items before they are actually removed from cache
+            # or updated
+            priority=1000
         )
         self.pubsub_service = APPubsubService(self)
         host.trigger.add("messageReceived", self._messageReceivedTrigger, priority=-1000)