$ git clone -n https://src.fedoraproject.org/rpms/rust-bitvec_helpers.git /var/lib/mock/f40-build-2215401-52428/root/chroot_tmpdir/scmroot/rust-bitvec_helpers
Cloning into '/var/lib/mock/f40-build-2215401-52428/root/chroot_tmpdir/scmroot/rust-bitvec_helpers'...
$ git fetch origin 3c523e36d70b2cc279a7c06bb872862468cb8030:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-bitvec_helpers
 * [new ref]         3c523e36d70b2cc279a7c06bb872862468cb8030 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3c523e3 update to 3.1.3 (resolves rhbz#2256117)