$ git clone -n https://src.fedoraproject.org/rpms/rust-cxx.git /var/lib/mock/f39-build-2186832-51376/root/chroot_tmpdir/scmroot/rust-cxx
Cloning into '/var/lib/mock/f39-build-2186832-51376/root/chroot_tmpdir/scmroot/rust-cxx'...
$ git fetch origin a5f614ab44e4e6947d63529b53f11600bc280173:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-cxx
 * [new ref]         a5f614ab44e4e6947d63529b53f11600bc280173 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a5f614a Update to version 1.0.114; Fixes RHBZ#2254857