gdbus-server-auth intermittent failure

Running ./gdbus-server-auth until it fails (took 7 minutes in a loop):

GLib-GIO:ERROR:../../../../Projects/jhbuild/glib/gio/tests/gdbus-server-auth.c:422:do_test_server_auth: assertion failed (libdbus_call.error.name == NULL): ("org.freedesktop.DBus.Error.NoReply" == NULL)
Bail out! GLib-GIO:ERROR:../../../../Projects/jhbuild/glib/gio/tests/gdbus-server-auth.c:422:do_test_server_auth: assertion failed (libdbus_call.error.name == NULL): ("org.freedesktop.DBus.Error.NoReply" == NULL)