$ git clone -n https://src.fedoraproject.org/rpms/rust-cxx-gen.git /var/lib/mock/f45-build-41133-779/root/chroot_tmpdir/scmroot/rust-cxx-gen
Cloning into '/var/lib/mock/f45-build-41133-779/root/chroot_tmpdir/scmroot/rust-cxx-gen'...
$ git fetch origin 43e02d1532e42600c0afa3154f73d85cf7f1cfcf:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-cxx-gen
 * [new ref]         43e02d1532e42600c0afa3154f73d85cf7f1cfcf -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 43e02d1 Update to version 1.0.200; Fixes RHBZ#2528935