$ git clone -n https://src.fedoraproject.org/rpms/rust.git /var/lib/mock/f40-build-807877-145348/root/chroot_tmpdir/scmroot/rust
Cloning into '/var/lib/mock/f40-build-807877-145348/root/chroot_tmpdir/scmroot/rust'...
$ git fetch origin 110b2ab26eb726b13724000ab2dd1c99cce93b67:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust
 * [new ref]         110b2ab26eb726b13724000ab2dd1c99cce93b67 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 110b2ab Update to 1.78.0