Weird control chars in some caldav TZID entries

[liedekef]

(copy/paste from sourceforge ticket)

Weird control chars in some caldav TZID entries are causing thunderbird to ignore that vevent entry. In my case, it seems to be with the TZID Europe/Brussels. In the davmail.log file I see these (the ctrl-M characters I can understand):

BEGIN:VTIMEZONE^M TZID:Europe/Brussels^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^M BEGIN:STANDARD^M DTSTART:16010101T020000^M TZOFFSETFROM:+0200^M TZOFFSETTO:+0100^M RRULE:FREQ=YEARLY;INTERVAL=1;BYDAY=-1SU;BYMONTH=10^M END:STANDARD^M BEGIN:DAYLIGHT^M DTSTART:16010101T010000^M TZOFFSETFROM:+0100^M TZOFFSETTO:+0200^M RRULE:FREQ=YEARLY;INTERVAL=1;BYDAY=-1SU;BYMONTH=3^M END:DAYLIGHT^M END:VTIMEZONE^M

And further down, for the event: DTSTART;TZID="Europe/Brussels^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@":20200107T100000^M DTEND;TZID="Europe/Brussels^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@^@":20200107T120000^M

Now it seems Thunderbird doesn't like these characters, and it seems to be only that TZID (Europe/Paris works ok it seems). I don't imagine that outlook users do this on purpose, so is this a bug in davmail upon parsing the timezone, or can davmail work around this and remove weird encoding chars from TZID entries? Btw: it is thunderbird itself that has issues with these control characters: saving the file as ics, removing these and then importing the resulting file in thunderbird works as expected. It seems in the past also tbsync had the same issue and they just removed the control-characters there.