$ git clone -n https://src.fedoraproject.org/rpms/perl-Test-Roo.git /var/lib/mock/f45-build-26821-619/root/chroot_tmpdir/scmroot/perl-Test-Roo
Cloning into '/var/lib/mock/f45-build-26821-619/root/chroot_tmpdir/scmroot/perl-Test-Roo'...
$ git fetch origin 4556e8fca8ad236a80bf2b52b7ebc2ce5981722a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-Test-Roo
 * [new ref]         4556e8fca8ad236a80bf2b52b7ebc2ce5981722a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4556e8f Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild