BUG #1937: Parts of information_schema only accessible to owner

The following bug has been logged online:

Bug reference: 1937
Logged by: Tony Marston
Email address: tony(at)marston-home(dot)demon(dot)co(dot)uk
PostgreSQL version: 8.0.3
Operating system: Windows XP
Description: Parts of information_schema only accessible to owner
Details:

I have been trying to access parts of the information_schema as an ordinary
user, not as owner, and I am encountering instances where I cannot retrieve
any rows at all, or where some of the columns are empty when they should not
be.

This sounds like a faulty implementation to me, with too many restrictions.
As far as I am concerned if I have access privileges on an object then I
should be able to see ALL information_schema details regarding that object.
Being able to view data in the information_schema does not give me the
ability to do anything that is not already permitted in the privilges
system, so why is access to such data being blocked?

As an example, in the view "information_schema.columns" I can only see the
entry in COLUMN_DEFAULT if I am the owner. Why is this? What is the logic
behind this decision? What possible security breach is blocked by witholding
this information?