$ git clone -n https://src.fedoraproject.org/rpms/rebase-helper.git /var/lib/mock/f40-build-1465803-23665/root/chroot_tmpdir/scmroot/rebase-helper
Cloning into '/var/lib/mock/f40-build-1465803-23665/root/chroot_tmpdir/scmroot/rebase-helper'...
$ git fetch origin 0a4bf5fda09c40f39835c2c5f67fba8ef61d6aca:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rebase-helper
 * [new ref]         0a4bf5fda09c40f39835c2c5f67fba8ef61d6aca -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0a4bf5f Update to 0.29.1 upstream release