$ git clone -n https://src.fedoraproject.org/rpms/rust-tokio-codec.git /var/lib/mock/f41-build-side-1-3134956-39764/root/chroot_tmpdir/scmroot/rust-tokio-codec
Cloning into '/var/lib/mock/f41-build-side-1-3134956-39764/root/chroot_tmpdir/scmroot/rust-tokio-codec'...
$ git fetch origin d4ec8e81a1df55699246efbced4505dbad8a669f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-tokio-codec
 * [new ref]         d4ec8e81a1df55699246efbced4505dbad8a669f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d4ec8e8 no longer needed