$ git clone -n https://src.fedoraproject.org/rpms/rust-tokio.git /var/lib/mock/f40-build-2170534-51021/root/chroot_tmpdir/scmroot/rust-tokio
Cloning into '/var/lib/mock/f40-build-2170534-51021/root/chroot_tmpdir/scmroot/rust-tokio'...
$ git fetch origin 49a5f1abb3ad3bcefc7dda4b7950b0cda2314ef1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-tokio
 * [new ref]         49a5f1abb3ad3bcefc7dda4b7950b0cda2314ef1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 49a5f1a Update to version 1.34.0; Fixes RHBZ#2248943