$ git clone -n https://src.fedoraproject.org/rpms/rust-prefixdevname.git /var/lib/mock/f39-build-1589426-38234/root/chroot_tmpdir/scmroot/rust-prefixdevname
Cloning into '/var/lib/mock/f39-build-1589426-38234/root/chroot_tmpdir/scmroot/rust-prefixdevname'...
$ git fetch origin 22d8b1bbe558136b4b6f0f6acce272de31456900:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-prefixdevname
 * [new ref]         22d8b1bbe558136b4b6f0f6acce272de31456900 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 22d8b1b Added the README