$ git clone -n https://src.fedoraproject.org/rpms/perl-bignum.git /var/lib/mock/f45-build-27625-625/root/chroot_tmpdir/scmroot/perl-bignum
Cloning into '/var/lib/mock/f45-build-27625-625/root/chroot_tmpdir/scmroot/perl-bignum'...
$ git fetch origin 516267a25687637db3c9d399b007be4d91eb52a1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-bignum
 * [new ref]         516267a25687637db3c9d399b007be4d91eb52a1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 516267a Perl 5.44 re-rebuild of bootstrapped packages