MacOS 10.12 Calendar 9.0 incorrect time zone info

On MacOS 10.12.5 set up for the Moscow Standard Time (+0300 GMT) Calendar 9.0 (2155.21) connected via CalDAV sends to a CalDAV server incorrect time zone specification.

The PUT request send by the Apple Calendar app has the following body:

BEGIN:VCALENDAR

VERSION:2.0

PRODID:-//Apple Inc.//Mac OS X 10.12.5//EN

CALSCALE:GREGORIAN

BEGIN:VTIMEZONE

TZID:Europe/Moscow

BEGIN:STANDARD

TZOFFSETFROM:+023017

DTSTART:20010101T000000

TZNAME:GMT+3

TZOFFSETTO:+023017

END:STANDARD

END:VTIMEZONE

BEGIN:VEVENT

CREATED:20170626T074022Z

UID:D6B69FF0-6F34-4F90-A745-824674F16B32

DTEND;TZID=Europe/Moscow:20170701T100000

TRANSP:OPAQUE

X-APPLE-TRAVEL-ADVISORY-BEHAVIOR:AUTOMATIC

SUMMARY:TestTestIndianiCal

DTSTART;TZID=Europe/Moscow:20170701T090000

DTSTAMP:20170626T074046Z

SEQUENCE:0

END:VEVENT

END:VCALENDAR

Note the TZOFFSETFROM/TZOFFSETTO attribute values. Normally they specify the HHMM offset relative to GMT. Here they contain completely bogus values (+023017). So, if he server uses these values to calculate the actual event time, the event time is shifted.