$ git clone -n https://src.fedoraproject.org/rpms/perl-B-COW.git /var/lib/mock/f41-build-815811-149783/root/chroot_tmpdir/scmroot/perl-B-COW
Cloning into '/var/lib/mock/f41-build-815811-149783/root/chroot_tmpdir/scmroot/perl-B-COW'...
$ git fetch origin 5785d019e0a6ab24a10f3bbc18b4aaf913de2079:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-B-COW
 * [new ref]         5785d019e0a6ab24a10f3bbc18b4aaf913de2079 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5785d01 Perl 5.40 rebuild