$ git clone -n https://src.fedoraproject.org/rpms/rust-fixed.git /var/lib/mock/f41-build-side-1-3124891-39482/root/chroot_tmpdir/scmroot/rust-fixed
Cloning into '/var/lib/mock/f41-build-side-1-3124891-39482/root/chroot_tmpdir/scmroot/rust-fixed'...
$ git fetch origin a51ca87cd12138ad03ba83247dbe1d0ca913e66c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-fixed
 * [new ref]         a51ca87cd12138ad03ba83247dbe1d0ca913e66c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a51ca87 Update to version 1.28.0