$ git clone -n https://src.fedoraproject.org/rpms/R-msm.git /var/lib/mock/f38-build-724290-99404/root/chroot_tmpdir/scmroot/R-msm
Cloning into '/var/lib/mock/f38-build-724290-99404/root/chroot_tmpdir/scmroot/R-msm'...
$ git fetch origin 1c3c9cff98910e0ad34ec52b5c5af28a0bb0e5c1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-msm
 * [new ref]         1c3c9cff98910e0ad34ec52b5c5af28a0bb0e5c1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 1c3c9cf R-maint-sig mass rebuild