$ git clone -n https://src.fedoraproject.org/rpms/perl-Math-Factor-XS.git /var/lib/mock/f45-build-24682-605/root/chroot_tmpdir/scmroot/perl-Math-Factor-XS
Cloning into '/var/lib/mock/f45-build-24682-605/root/chroot_tmpdir/scmroot/perl-Math-Factor-XS'...
$ git fetch origin 5d8ba09fbe981d99fe48babf8b3a6a8c0ddbadae:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-Math-Factor-XS
 * [new ref]         5d8ba09fbe981d99fe48babf8b3a6a8c0ddbadae -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5d8ba09 Perl 5.44 rebuild