$ git clone -n https://src.fedoraproject.org/rpms/rust-hashbrown0.12.git /var/lib/mock/f45-build-42303-792/root/chroot_tmpdir/scmroot/rust-hashbrown0.12
Cloning into '/var/lib/mock/f45-build-42303-792/root/chroot_tmpdir/scmroot/rust-hashbrown0.12'...
$ git fetch origin 83e2d3508fb806ea75200a00389406e1457bfebf:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-hashbrown0.12
 * [new ref]         83e2d3508fb806ea75200a00389406e1457bfebf -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 83e2d35 Regenerate with rust2rpm v28