$ git clone -n https://src.fedoraproject.org/rpms/rust-blocking.git /var/lib/mock/f39-build-2204419-51953/root/chroot_tmpdir/scmroot/rust-blocking
Cloning into '/var/lib/mock/f39-build-2204419-51953/root/chroot_tmpdir/scmroot/rust-blocking'...
$ git fetch origin b938638fb52ce10b1a10ded7abdb30664b8cd3aa:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-blocking
 * [new ref]         b938638fb52ce10b1a10ded7abdb30664b8cd3aa -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b938638 Update to version 1.5.1; Fixes RHBZ#2240650