$ git clone -n https://src.fedoraproject.org/rpms/rust-rcgen.git /var/lib/mock/f42-build-side-1-3581443-46829/root/chroot_tmpdir/scmroot/rust-rcgen
Cloning into '/var/lib/mock/f42-build-side-1-3581443-46829/root/chroot_tmpdir/scmroot/rust-rcgen'...
$ git fetch origin b6729a68087aa544e480c0208eca151f20ba97ac:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-rcgen
 * [new ref]         b6729a68087aa544e480c0208eca151f20ba97ac -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b6729a6 Update to version 0.13.2; Fixes RHBZ#2333616