$ git clone -n https://src.fedoraproject.org/rpms/perl-Math-Prime-XS.git /var/lib/mock/f41-build-816510-150225/root/chroot_tmpdir/scmroot/perl-Math-Prime-XS
Cloning into '/var/lib/mock/f41-build-816510-150225/root/chroot_tmpdir/scmroot/perl-Math-Prime-XS'...
$ git fetch origin 1a408bb54ccca9335e0006cb5a41f0c528703276:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-Math-Prime-XS
 * [new ref]         1a408bb54ccca9335e0006cb5a41f0c528703276 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 1a408bb Perl 5.40 rebuild