Fix `test__generate_timeperiods` to that it actually calls `_generate_timeperiods` instead of `_generate_targetperiods`.
Fix `test__generate_timeperiods` to that it actually calls `_generate_timeperiods` instead of `_generate_targetperiods`.

mercycorps/TolaActivity,mercycorps/TolaActivity,mercycorps/TolaActivity,mercycorps/TolaActivity