$ git clone -n https://src.fedoraproject.org/rpms/perl-Child.git /var/lib/mock/f45-build-22276-590/root/chroot_tmpdir/scmroot/perl-Child
Cloning into '/var/lib/mock/f45-build-22276-590/root/chroot_tmpdir/scmroot/perl-Child'...
$ git fetch origin c8070a8df2cacd1fdcd5b61d5bfa3b359796fa63:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-Child
 * [new ref]         c8070a8df2cacd1fdcd5b61d5bfa3b359796fa63 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c8070a8 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild