`time_with_zone.zone.should == (time_with_zone - 60*60).zone` fails when
the time is immediately before the change of summer time.
20200328T232504Z.fail.html.gz
```
1)
Time#+ preserves time zone FAILED
Expected "CET" == "CEST"
to be truthy but was false
```
It is acceptable as it fails at most twice per year, but it would be
good to use near time objects to reduce the possibility.