8.3 vs 8.2 sql compatiblity issue

Hi,
Just running some queries that have worked from 7.4 through 8.2 and they
don't seem to work on 8.3.

select case when a.attnum = any(conkey) then true else false end from
pg_constraint where contype = 'p' and conrelid = c.oid

This one is puking on a.attnum = any(conkey)

returns the following error:

SQL State: 42883
ERROR: operator does not exist: smallint = text
HINT: No operator matches the given name and argument type(s). You might
need to add explicit type casts.
0 Record(s) Returned
--------------------------------------------------------------------

I am actually getting a lot of these operator does not exist errors in 8.3
another one I get is operator does not exist for char=integer

i.e.

attnum = pi.indkey[0]) used to work but fails in 8.3

Ideas?

Thanks,

Tony