Implicit transaction not rolling back after error

I'm having difficulty locating the source of a problem our webapp has been running into. Multiple Google searches have failed me, so I'm hoping someone here can help troubleshoot.

When some clients (psql, the webapp) connect to our production database, they become stuck in an aborted transaction after any failed statement. For example:

$ psql --version
psql (PostgreSQL) 9.0.5
$ psql test
psql (9.0.5)
SSL connection (cipher: DHE-RSA-AES256-SHA, bits: 256)
Type "help" for help.

test=> SELECT foo;
ERROR: column "foo" does not exist
LINE 1: SELECT foo;
^
test=> SELECT VERSION();
ERROR: current transaction is aborted, commands ignored until end of transaction block

Of course, there is no explicit transaction around the first statement, but no commands can be issued until after a ROLLBACK.

Stangely, I don't encounter this issue if I connect directly from my development machine.

$ psql --version
psql (PostgreSQL) 9.2.1
$ psql --host $HOST test
psql (9.2.1, server 9.0.5)
WARNING: psql version 9.2, server version 9.0.
Some psql features might not work.
SSL connection (cipher: DHE-RSA-AES256-SHA, bits: 256)
Type "help" for help.

onelogin_production=> SELECT foo;
ERROR: column "foo" does not exist
LINE 1: SELECT foo;
^
onelogin_production=> SELECT VERSION();
version
-------------------------------------------------------------------------------------------------------------
PostgreSQL 9.0.5 on x86_64-pc-linux-gnu, compiled by GCC gcc-4.4.real (Ubuntu 4.4.3-4ubuntu5) 4.4.3, 64-bit
(1 row)

I also don't encounter the issue if I connect to the running 9.2 daemon on my development machine either.

Our production webapp also suffers from this problem (which is how we noticed it in the first place). It connects to the PostgreSQL daemon through a Ruby library (pg) which wraps libpq5. I assumed the only commonality between psql and our application was libpq5, so upgraded it to a later version (9.2.2) with no luck.

Does anyone know what this might be? Is it a bug? A feature? A configuration issue? I'm kind of at a loss at this point.

Thanks in advance for your help.

--
Stephen Touset
Senior Software Engineer
stephen(dot)touset(at)onelogin(dot)com