$ git clone -n https://src.fedoraproject.org/rpms/perl-Math-Libm.git /var/lib/mock/f45-build-24713-605/root/chroot_tmpdir/scmroot/perl-Math-Libm
Cloning into '/var/lib/mock/f45-build-24713-605/root/chroot_tmpdir/scmroot/perl-Math-Libm'...
$ git fetch origin d3e4906f29604730166ed504751eba2c3ae620d1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-Math-Libm
 * [new ref]         d3e4906f29604730166ed504751eba2c3ae620d1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d3e4906 Perl 5.44 rebuild