update-manager: actually remember that we asked the user

Otherwise we get that annoying question every time the git version changes.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

desktop-widgets/updatemanager.cpp

@@ -120,6 +120,7 @@ void UpdateManager::requestReceived()
 			response.setIcon(QMessageBox::Question);
 			response.setWindowModality(Qt::WindowModal);
 			update_settings->set_dont_check_for_updates(response.exec() != QMessageBox::Accepted);
+			update_settings->set_dont_check_exists(true);
 		}
 	}
 }