$ git clone -n https://src.fedoraproject.org/rpms/rebase-helper.git /var/lib/mock/f40-build-2060506-49160/root/chroot_tmpdir/scmroot/rebase-helper
Cloning into '/var/lib/mock/f40-build-2060506-49160/root/chroot_tmpdir/scmroot/rebase-helper'...
$ git fetch origin 19c7b48b2f233b66c935b914aaf8d31f5687d15b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rebase-helper
 * [new ref]         19c7b48b2f233b66c935b914aaf8d31f5687d15b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 19c7b48 Actually use PyPI source