$ git clone -n https://src.fedoraproject.org/rpms/rust-base-x.git /var/lib/mock/f41-build-side-1-2934430-35233/root/chroot_tmpdir/scmroot/rust-base-x
Cloning into '/var/lib/mock/f41-build-side-1-2934430-35233/root/chroot_tmpdir/scmroot/rust-base-x'...
$ git fetch origin e0c90c05c2cfee663da6062aab77a3be77361eeb:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-base-x
 * [new ref]         e0c90c05c2cfee663da6062aab77a3be77361eeb -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e0c90c0 unused leaf package for more than two release cycles