libnm-glib: better handling of missing user settings service

If it's not running or we can't spawn it (it's not supposed to be
autospawned anyway) we should just ignore the error and poke clients
that we've tried and failed to get user settings instead of warning
with an annoying message.

libnm-glib/nm-remote-settings.c

@@ -166,12 +166,26 @@ fetch_connections_done (DBusGProxy *proxy,
 	int i;
 
 	if (error) {
-		g_warning ("%s: error fetching %s connections: (%d) %s.",
-		           __func__,
-		           priv->scope == NM_CONNECTION_SCOPE_USER ? "user" : "system",
-		           error->code,
-		           error->message ? error->message : "(unknown)");
+		gboolean is_spawn_error = FALSE;
+
+		/* Don't warn if the user settings service wasn't running since that's
+		 * just annoying when running headless.
+		 */
+		if (   g_error_matches (error, DBUS_GERROR, DBUS_GERROR_SERVICE_UNKNOWN)
+		    || g_error_matches (error, DBUS_GERROR, DBUS_GERROR_NAME_HAS_NO_OWNER))
+			is_spawn_error = TRUE;
+
+		if (!is_spawn_error || priv->scope == NM_CONNECTION_SCOPE_SYSTEM) {
+			g_warning ("%s: error fetching %s connections: (%d) %s.",
+				       __func__,
+				       priv->scope == NM_CONNECTION_SCOPE_USER ? "user" : "system",
+				       error->code,
+				       error->message ? error->message : "(unknown)");
+		}
 		g_clear_error (&error);
+
+		/* We tried to read connections and failed */
+		g_signal_emit_by_name (self, NM_SETTINGS_INTERFACE_CONNECTIONS_READ);
 		return;
 	}