$ git clone -n https://src.fedoraproject.org/rpms/rust-cxxbridge-macro.git /var/lib/mock/f39-build-1495021-34543/root/chroot_tmpdir/scmroot/rust-cxxbridge-macro
Cloning into '/var/lib/mock/f39-build-1495021-34543/root/chroot_tmpdir/scmroot/rust-cxxbridge-macro'...
$ git fetch origin 42fba613a8f5630f41a836cafad790c9abde42a7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-cxxbridge-macro
 * [new ref]         42fba613a8f5630f41a836cafad790c9abde42a7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 42fba61 Update to version 1.0.109 (rhbz#2242980)