$ git clone -n https://src.fedoraproject.org/rpms/perl-B-Debug.git /var/lib/mock/f45-build-21835-588/root/chroot_tmpdir/scmroot/perl-B-Debug
Cloning into '/var/lib/mock/f45-build-21835-588/root/chroot_tmpdir/scmroot/perl-B-Debug'...
$ git fetch origin ca89787f0995437c958ab831ff93a3fc7e162f78:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-B-Debug
 * [new ref]         ca89787f0995437c958ab831ff93a3fc7e162f78 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ca89787 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild