BUG #8515: Random 'relation "..." does not exist'

The following bug has been logged on the website:

Bug reference: 8515
Logged by: Nicolas Buduroi
Email address: nbuduroi(at)gmail(dot)com
PostgreSQL version: 9.2.4
Operating system: ArchLinux
Description:

We've recently migrated an application from MySQL to Postgres and I've been
experiencing some really strange and random bugs. The application is a
pretty simple Rails application and the Postgres setup is the default one
provided by ArchLinux.

Basically, at some point a query, update or insert will not work and
complain about a table not existing, but that table was used without any
issue previously. Closing the running connection to the database and
reconnecting make that error disappear. Two concurrent connections (one from
a console and another from the app) could be contradicting themselves, one
giving the error and the other not.

This only happen on a development machine which is running version 9.2.4 of
Postgres. We've not encountered this error on our production/staging/ci
servers which are running Postgres 9.1.9 version.