[horde] CalDAV timezone troubles bug#13866

[Steffen]

See: https://bugs.horde.org/ticket/13866

I had trouble to upload an event from a CalDAV client for the 14th Feb 
2015 14:00 Timezone Europe/Berlin. It happend for KDE Akonadi / Korganizer 
as well as when I re-submit the entry that I fetched via GET from Horde 
back to Horde.

The problem seems to be that Icalendar/Vtimezones.php returns a single 
entry for the requested year for timezones defined via RRULE. For 
Europe/Berlin the function returns one entry for daylight in March 2015 
and one in October 2015 for standard time, but none for 2014 although the 
RRULE applies for 1981 up.

That forced _parseTZID() in Icalendar.php to choose another timezone 
definition entry with an inappropriate timezone offset.

I uploaded a patch returning the entries for $year and $year-1 for RRULEs, 
too.

Note: Lightning does not have this problem, maybe because it does upload 
only one timezone entry. So for 14.Feb no timezone definition could be 
found and the _parseTZID() seems to keep the time unchanged.

Does somebody had the same trouble with CalDAV and time offset and could 
test the patch?

-- 
Steffen