BUG #10748: xmax is not resetting properly with FOR UPDATE

The following bug has been logged on the website:

Bug reference:      10748
Logged by:          Alicja Kucharczyk
Email address:      pinker@onet.eu
PostgreSQL version: 9.3.4
Operating system:   RedHat
Description:

The problem is described here:
http://stackoverflow.com/questions/24382158/strange-cleanup-behaviour-with-for-update

The main problem is that xmax values stays set with xid of transaction that
has already committed. The documentation says: "The identity (transaction
ID) of the deleting transaction, or zero for an undeleted row version. It is
possible for this column to be nonzero in a visible row version. That
usually indicates that the deleting transaction hasn't committed yet, or
that an attempted deletion was rolled back."

I have used this feature for a queue to avoid locking, but it doesn't work
together with FOR UPDATE clause.

best regards,
A.Kucharczyk