$ git clone -n https://src.fedoraproject.org/rpms/perl-Alien-Build-MB.git /var/lib/mock/f45-build-21642-587/root/chroot_tmpdir/scmroot/perl-Alien-Build-MB
Cloning into '/var/lib/mock/f45-build-21642-587/root/chroot_tmpdir/scmroot/perl-Alien-Build-MB'...
$ git fetch origin 010c53e47694c11d0ac3ebf4ffef392792602c5e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-Alien-Build-MB
 * [new ref]         010c53e47694c11d0ac3ebf4ffef392792602c5e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 010c53e Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild