lobject (conn) can segfault with bad parameter

Hmm, I tested what happens when doing psycopg2.extensions.cursor(<not a conn object>) and the result is weird - the cursor object is created and it lets you do operations but fails in unexpected ways - the query fails with the exception "cursor already closed" which is not very descriptive IMHO.

Really? It doesn't seem so:

>>> cur = psycopg2.extensions.cursor([])
TypeError: argument 1 must be psycopg2._psycopg.connection, not list

Hmm, I now see I'm on an earlier version actually (2.4.5)

>>> import psycopg2.extensions as ex
>>> ex.cursor([])
<cursor object at 0x00000000026B9B40; closed: 0>

Thanks for the fix, I should probably update...