Due date specified as DATE is changed to DATETIME with year 1900

[fwc]

I have a todo with due date 21.04, specified as DUE;VALUE=DATE:20210421 in the .ics-file.

When I open this todo with todo edit <id> and save it again directly, without changes, the due date is changed to DUE;VALUE=DATE-TIME:19000420T230000Z.

So my todo is now due on 21.04.1900.

.ics-file before editing with todoman

BEGIN:VCALENDAR
VERSION:2.0
PRODID:+//IDN tasks.org//android-110903//EN
BEGIN:VTODO
DTSTAMP:20210420T111823Z
UID:3643130479634528538
CREATED:20210420T105907Z
LAST-MODIFIED:20210420T111805Z
SUMMARY:Test
X-APPLE-SORT-ORDER:608725011
DUE;VALUE=DATE:20210421
END:VTODO
END:VCALENDAR

.ics-file after editing with todoman

BEGIN:VCALENDAR
VERSION:2.0
PRODID:+//IDN tasks.org//android-110903//EN
BEGIN:VTODO
CREATED;VALUE=DATE-TIME:20210420T105907Z
DTSTAMP;VALUE=DATE-TIME:20210420T111823Z
DUE;VALUE=DATE-TIME:19000420T230000Z
LAST-MODIFIED;VALUE=DATE-TIME:20210420T112108Z
SEQUENCE:2
STATUS:NEEDS-ACTION
SUMMARY:Test
UID:3643130479634528538
X-APPLE-SORT-ORDER:608725011
END:VTODO
END:VCALENDAR

[fwc]

for reproducing, set date_format in the configuration to date_format = "%d.%m.".

The initial date (2021-04-21) is then displayed in this format ("21.04."), and 'parsed back' into a datetime-object when saving, but the year is lost during the process.

When re-parsing the date, we run into the following code in interactive.py:

    def _save_inner(self):
        # ...
        self.todo.due = self.formatter.parse_datetime(self.due)
        # ...

• Before this line, self.todo.due is still the initial datetime.date-object (2021-04-21).
• self.due is the string value that was displayed, which in turn is the formatted date-object: "21.04.".
• During parsing, self.due matches the date_format, so it's parsed with datetime.strptime, which sets the year to 1900:

  • >>> datetime.strptime("21.04.", "%d.%m.")
    # returns: datetime.datetime(1900, 4, 21, 0, 0)