BUG #3260: Subtracting intervals

The following bug has been logged online:

Bug reference:      3260
Logged by:          Dhugael McLean
Email address:      box@yourtechonline.com
PostgreSQL version: 8.1.8
Operating system:   FreeBSD
Description:        Subtracting intervals
Details:

select '1 day'::interval - '55 minutes'::interval;

    ?column?
-----------------
 1 day -00:55:00

If the interval periods are both minutes (hours - hours, days - days, etc),
this works fine. Days - minutes seems to fail. This should output 23:05:00.

In case this was some weird casting error, I checked:
select interval '1 day' - interval '55 minutes';
and that failed as well.