core (main): ensure that reactor is running during post initialisation:

In background mode, the reactor is run later, this may cause troubles during some
initialisation. This has notably be seen for PB bridge which was not correctly listening
to the socket.

libervia/backend/core/main.py

@@ -105,7 +105,10 @@ class LiberviaBackend(service.Service):
         else:
             self.local_shared_path = None
 
-        defer.ensureDeferred(self._post_init())
+        # XXX: we use callLater here to be sure that the reactor is running when doing
+        #   post initialisation. This is notably important in background mode where
+        #   reactor is run later.
+        reactor.callLater(0, lambda: defer.ensureDeferred(self._post_init()))
 
     @property
     def version(self):