From evolution’s widgets/misc/e-dateedit, a custom date field:
e_utf8_strftime (buffer, sizeof (buffer), _("%m/%d/%Y"), &tmp_tm);
You see that _("%m/%d/%Y") there? That means you’ll only have a sane
(that is, non-American) date format if you’re running with LC_MESSAGES
set to the format you prefer for dates and such. It also means extra
work for the translator as well as possible errors due to translators
having a personal preferred way to write dates. Using “%x” instead
fixes the problem (verified by binary patching
/usr/lib/evolution/2.6/libemiscwidgets.so.0.0.0, since I don’t have a
very recent evolution source handy) and gives me nice and (semi-)sane
dates.
Bug not yet filed due to me being aboard an aeroplane.
Now I just have to fix the way to write dates in nb_NO.UTF-8 into the
same as ISO-8601, but that should be easy enough.
Update. I meant %x, not %c, of course