$ git clone -n https://src.fedoraproject.org/rpms/rust-cxx.git /var/lib/mock/f40-build-2652612-66895/root/chroot_tmpdir/scmroot/rust-cxx
Cloning into '/var/lib/mock/f40-build-2652612-66895/root/chroot_tmpdir/scmroot/rust-cxx'...
$ git fetch origin 96ea2c69d2c1e1b294b00679e5b09cc4550709b5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-cxx
 * [new ref]         96ea2c69d2c1e1b294b00679e5b09cc4550709b5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 96ea2c6 Update to version 1.0.120 (rhbz#2271158)