Update rebellion calculation to be the same as TWFY
Update rebellion calculation to be the same as TWFY

It was changed in this commit upstream: https://github.com/mysociety/theyworkforyou/commit/edb0c6f9bd7ad2b57f9befee42d45c9059d01bb1

archoo/twfy,archoo/twfy,openaustralia/twfy,openaustralia/twfy,openaustralia/twfy,openaustralia/twfy,archoo/twfy,openaustralia/twfy,archoo/twfy,archoo/twfy,openaustralia/twfy,archoo/twfy,archoo/twfy