that's because duration is set to some arbitrary value in TestGetEventsATZDT. the end dates were just not tested, so this was no issue until now. to get an hour, we cannot use a duration of `0.1` but `1d/24h`, as:
```>>> DateTime(2011,11,11,11,00) + 1/24.
DateTime('2011/11/11 12:00:00 GMT+1')
```