$ git clone -n https://src.fedoraproject.org/rpms/rust-color-spantrace.git /var/lib/mock/f42-build-side-1-3540446-46574/root/chroot_tmpdir/scmroot/rust-color-spantrace
Cloning into '/var/lib/mock/f42-build-side-1-3540446-46574/root/chroot_tmpdir/scmroot/rust-color-spantrace'...
$ git fetch origin f17d160956aeaaf078ab6f68f82c6fafef6578eb:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-color-spantrace
 * [new ref]         f17d160956aeaaf078ab6f68f82c6fafef6578eb -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f17d160 Update to version 0.3.0; Fixes RHBZ#2363851