7.2 -> 7.3 incompatibility

I found an example of a casting problem in our source code now that we're
running 7.3:

SELECT CURRENT_DATE - EXTRACT(DOW FROM CURRENT_DATE);

(Get's the start of the week);

This worked in 7.2, but fails in 7.3 with:

ERROR: Unable to identify an operator '-' for types 'date' and 'double
precision' You will have to retype this query using an explicit cast

I'm not sure really why DOW needs to be double precision, but hey...

I guess this isn't so important, as there are workarounds (which are
complicated...)

Chris