connection.closed attribute is not set properly on localconnections

Formatting did not go well through web form. The reproduction is below.

$ python
Python 2.7.5+ (default, Sep 19 2013, 13:48:49) 
[GCC 4.8.1] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import psycopg2
>>> conn = psycopg2.connect("dbname=tst host=/tmp")
>>> conn.closed
0
>>> # Issuse CTRL-Z
[1]+  Stopped                 python
$ service postgresql restart
 * Restarting PostgreSQL 9.1 database server
   ...done.
$ fg
python


>>> cur = conn.cursor()
>>> cur.execute("SELECT 1")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
psycopg2.OperationalError: server closed the connection unexpectedly
        This probably means the server terminated abnormally
        before or while processing the request.

>>> conn.closed    # <------------ Should be greater then zero!
0
>>> psycopg2.__version__
'2.5.2 (dt dec pq3 ext)'
>>>

BTW, to emphasize, that if one connects through TCP and not local socket, then closed attribute is populated properly.

Ugh, thank you for the clarification, I wouldn't have expected such a difference.

Yeah, I've spotted it while working on Momoko - dead connection detection stopped functioning when one connects through local socket.

In debug mode, executing into a broken socket connection:

In [4]: cur.execute('select 1')
[19233] psyco_curs_execute: starting execution of new query
[19233] curs_execute: pg connection at 0x2095ff0 OK
[19233] pq_begin_locked: pgconn = 0x2095ff0, autocommit = 0, status = 1
[19233] pq_execute_command_locked: pgconn = 0x2095ff0, query = BEGIN
[19233] pq_execute_command_locked: PQexec returned NULL
[19233] pq_complete_error: pgconn = 0x2095ff0, pgres = (nil), error = server closed the connection unexpectedly
    This probably means the server terminated abnormally
    before or while processing the request.

[19233] psyco_curs_execute: res = -1, pgres = (nil)

In a tcp connection instead:

[19233] psyco_curs_execute: starting execution of new query
[19233] curs_execute: pg connection at 0x20e8120 OK
[19233] pq_begin_locked: pgconn = 0x20e8120, autocommit = 0, status = 1
[19233] pq_execute_command_locked: pgconn = 0x20e8120, query = BEGIN
[19233] pq_execute_command_locked: result was not COMMAND_OK (7)
[19233] pq_complete_error: pgconn = 0x20e8120, pgres = 0x2158e30, error = (null)
[19233] pq_raise: PQresultErrorMessage: err=FATAL:  terminating connection due to administrator command
SSL connection has been closed unexpectedly

so this should be the branch point: PQexec returning NULL vs. a "not ok" result.

Verified: works for me at https://github.com/dvarrazzo/psycopg.git#d1e1243ba851641feb2920148a...

Waiting for 2.5.3.
Thanks!