$ git clone -n https://src.fedoraproject.org/rpms/rust-which.git /var/lib/mock/f42-build-side-1-3512417-46069/root/chroot_tmpdir/scmroot/rust-which
Cloning into '/var/lib/mock/f42-build-side-1-3512417-46069/root/chroot_tmpdir/scmroot/rust-which'...
$ git fetch origin ce1d5b85eb3b0f16df364d8bd1c7f0fde7badde6:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-which
 * [new ref]         ce1d5b85eb3b0f16df364d8bd1c7f0fde7badde6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ce1d5b8 Update to version 7.0.2; Fixes RHBZ#2344152