Difference between 7.2 and 7.3, possible bug?

create table test (col_a bigint);
update test set col_a = nullif('200', -1);

The above works fine on 7.2 but the update fails on 7.3b2 with the
following error:

ERROR: column "col_a" is of type bigint but expression is of type text
You will need to rewrite or cast the expression

Is this change in behavior intentional or is it a bug?

This situation is occuring because of two changes. The first being the
difference in how the server is handling the above update in 7.2 vs.
7.3. The second is a change in the jdbc driver in 7.3. The actual
update in jdbc looks like:
update test set col_a = nullif(?, -1);
and a "setLong(1, 200)" call is being done. In 7.2 the jdbc driver
bound the long/bigint value as a plain number, but in 7.3 it binds it
with quotes making it type text and exposing the change in server
behavior. This change was made in the jdbc driver to work around the
fact that indexes are not used for int2 or int8 columns unless the value
is enclosed in quotes (or an explicit cast is used). I am not sure if
the recent changes for implicit casts fixes this index usage problem in
the server or not.

So I have three options here:

1) if this is a server bug wait for a fix for 7.3
2) revert the jdbc driver back to not quoting int2 and int8 values
- If the server now handles using indexes on int2/int8 columns then
this should be done anyway
- It the server still has problems with using indexes without the
quotes then this removes an often requested bugfix/workaround
for the index usage problem
3) Just have people rework their sql to avoid the change in behavior

Any suggestions?

thanks,
--Barry