$ git clone -n https://src.fedoraproject.org/rpms/R-reprex.git /var/lib/mock/f43-build-side-110352-58924007-6569299/root/chroot_tmpdir/scmroot/R-reprex
Cloning into '/var/lib/mock/f43-build-side-110352-58924007-6569299/root/chroot_tmpdir/scmroot/R-reprex'...
$ git fetch origin 001068e5c5fc0193f1114234f37d95b4d8b23ec5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-reprex
 * [new ref]         001068e5c5fc0193f1114234f37d95b4d8b23ec5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 001068e Update to latest version