$ git clone -n https://src.fedoraproject.org/rpms/rubygem-rdiscount.git /var/lib/mock/f42-build-865205-172845/root/chroot_tmpdir/scmroot/rubygem-rdiscount
Cloning into '/var/lib/mock/f42-build-865205-172845/root/chroot_tmpdir/scmroot/rubygem-rdiscount'...
$ git fetch origin 4f30d1b2f64e5508c0660ebe62cf2d70494a216a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-rdiscount
 * [new ref]         4f30d1b2f64e5508c0660ebe62cf2d70494a216a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4f30d1b Rebuilt for https://fedoraproject.org/wiki/Changes/Ruby_3.4