Zero length ranges, such as for events without a DTEND could be
considered to overlap a range if they were at exactly the end of the
range. The end of a range however is the first date that is supposed to
not overlap, so a zero-length range on exactly this point should not be
considered overlapping.
This fixes cases where all-day events from the next month could show up
on the same day of the current month if they did not have a DTEND.
This also adds tests for all possible cases of such zero-length events
overlapping.
Fixes https://gitlab.gnome.org/GNOME/gnome-calendar/-/issues/701
On systems without anything providing the org.freedesktop.timedate1
interface, the timezone returned by the monitor would always be NULL,
because it was never set. This can lead to crashes in places that expect
the monitor to always return a valid timezone. So in that case use the
local timezone from when the monitor got initialized.
Fixes https://gitlab.gnome.org/GNOME/gnome-calendar/-/issues/703
Sebastian Keller