BUG #6254: COPY ... TO .. CSV sometimes doesn't escape strings

The following bug has been logged online:

Bug reference:      6254
Logged by:          Andrew Kerr
Email address:      andrew.kerr@unrulymedia.com
PostgreSQL version: 9.0.5
Operating system:   CentOS 5.4
Description:        COPY ... TO .. CSV sometimes doesn't escape strings
Details:

Query of this form:

copy (select
 col1,col2
from mytable)
 to 'output.csv' with (format csv, force_quote *);

where some selected columns are text sometimes fails to escape quotes (with
another quote) in text.

On which rows this happens varies with different runs.

Sometimes a field will have some quotes escaped and some not.

Running on a 90 million row table.