kopano rrule

$ diff -uNrBbd libicalmapi/vconverter.cpp.org libicalmapi/vconverter.cpp
--- libicalmapi/vconverter.cpp.org      2016-12-16 09:56:35.782499500 +0100
+++ libicalmapi/vconverter.cpp  2016-12-16 09:57:38.417999500 +0100
@@ -1551,9 +1551,10 @@
                return hrSuccess;
        }

-       if (m_iCurrentTimeZone == m_mapTimeZones->end())
                // if we have an RRULE, we must have a timezone
-               return MAPI_E_CORRUPT_DATA;
+       // some clients, like thunderbird 45.5.1 don't add it so then work around it by assuming UTC
+       if (m_iCurrentTimeZone == m_mapTimeZones->end())
+               m_iCurrentTimeZone = m_mapTimeZones->begin();

        HRESULT hr = icRecClass.HrParseICalRecurrenceRule(m_iCurrentTimeZone->second, lpicEventRoot, lpicEvent, bIsAllday, m_lpNamedProps, lpIcalItem);
        if (hr != hrSuccess)