$ git clone -n https://src.fedoraproject.org/rpms/bst-external.git /var/lib/mock/f39-build-1557511-37287/root/chroot_tmpdir/scmroot/bst-external
Cloning into '/var/lib/mock/f39-build-1557511-37287/root/chroot_tmpdir/scmroot/bst-external'...
$ git fetch origin f81ec6d6a9c2cd41f77d769eab926495a49f5cdc:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/bst-external
 * [new ref]         f81ec6d6a9c2cd41f77d769eab926495a49f5cdc -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f81ec6d Rebuilt for https://fedoraproject.org/wiki/Fedora_39_Mass_Rebuild