empty string in composite data types

Hi,

I noticed some (imho) odd behaviour while using composite data types.
Empty strings will be returned as None instead of '' in Python.

For example:

sql> CREATE TYPE testtype AS (id INT, label TEXT);

python> import psycopg2
python> import psycopg2.extras
python> db = psycopg2.connect(...)
python> caster = psycopg2.extras.register_composite('testtype', db)
python> cursor = db.cursor()
python> cursor.execute("SELECT (1, '')::testtype")
python> cursor.fetchone()[0]
testtype(id=1, label=None)

Is this behaviour intended? Or is there some flag I don't know about (I
have found none) that gives me empty strings instead?

Any help would be appreciated.

Cheers,
Chris