$ git clone -n https://src.fedoraproject.org/rpms/rust-self_cell.git /var/lib/mock/f39-build-2101502-50501/root/chroot_tmpdir/scmroot/rust-self_cell
Cloning into '/var/lib/mock/f39-build-2101502-50501/root/chroot_tmpdir/scmroot/rust-self_cell'...
$ git fetch origin 0b4c34acaaa4937bbd366e1a95ad61d7cfa4110b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-self_cell
 * [new ref]         0b4c34acaaa4937bbd366e1a95ad61d7cfa4110b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0b4c34a Update to version 1.0.3; Fixes RHBZ#2255425