$ git clone -n https://src.fedoraproject.org/rpms/rust-which.git /var/lib/mock/f42-build-side-1-3573370-46767/root/chroot_tmpdir/scmroot/rust-which
Cloning into '/var/lib/mock/f42-build-side-1-3573370-46767/root/chroot_tmpdir/scmroot/rust-which'...
$ git fetch origin 0be007f13c388f83af23ab125b0bf48a36dcae59:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-which
 * [new ref]         0be007f13c388f83af23ab125b0bf48a36dcae59 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0be007f Update to version 7.0.3; fixes RHBZ#2358454