Comment 2 for bug 1707945

The undocumented location is implemented in the file pkcs11/gkm/gkm-util.c

gkm_util_locate_keyrings_directory (void)
{
[…]
        old_directory = g_build_filename (g_get_home_dir (), ".gnome2", "keyrings", NULL);
        new_directory = g_build_filename (g_get_user_data_dir (), "keyrings", NULL);

        /*
         * If the new XDG directory doesn't exist, and the old one does,
         * use the old one, otherwise create/use the new XDG location.
         */

[…]}