BUG #8439: phantom dupe key violation

The following bug has been logged on the website:

Bug reference: 8439
Logged by: Michael McInness
Email address: m(dot)mcinness1(at)gmail(dot)com
PostgreSQL version: 9.2.0
Operating system: Ubuntu 12.0.4
Description:

I apologize in advance -- I cannot reproduce this using a backup database
and after deleting one of the rows in question the issue is resolved, but I
feel compelled to report the problem in case there is a similar issue that
is being tracked:

a query such as 'select * from foo where foo_id = 1' on a table with a
primary key created as such: create table foo (foo_id serial primary
key,...) was producing two rows:

foo_id
--------
1
3

Because it's a production system, I needed to address immediately. After
deleting then re-inserting the row with foo_id = 3, the problem went away,
of course. This really happened -- I wouldn't dream of wasting your time!

Thanks and regards,
Michael