$ git clone -n https://src.fedoraproject.org/rpms/perl-B-Generate.git /var/lib/mock/f40-build-731715-104578/root/chroot_tmpdir/scmroot/perl-B-Generate
Cloning into '/var/lib/mock/f40-build-731715-104578/root/chroot_tmpdir/scmroot/perl-B-Generate'...
$ git fetch origin b4aad15086c68a7094dc2d43cd5f93a86cc19be2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-B-Generate
 * [new ref]         b4aad15086c68a7094dc2d43cd5f93a86cc19be2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b4aad15 Rebuilt for https://fedoraproject.org/wiki/Fedora_39_Mass_Rebuild