$ git clone -n https://src.fedoraproject.org/rpms/stgit.git /var/lib/mock/f42-build-side-1-3573389-46767/root/chroot_tmpdir/scmroot/stgit
Cloning into '/var/lib/mock/f42-build-side-1-3573389-46767/root/chroot_tmpdir/scmroot/stgit'...
$ git fetch origin b17969a14ba6d1bb1b16acc918ae7600708b0e16:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/stgit
 * [new ref]         b17969a14ba6d1bb1b16acc918ae7600708b0e16 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b17969a Update to version 2.5.3; Fixes RHBZ#2346052