BUG #4789: ERROR 22008 on timestamp import

The following bug has been logged online:

Bug reference: 4789
Logged by: Robert Kruuus
Email address: robert(dot)kruus(at)gov(dot)sk(dot)ca
PostgreSQL version: 8.3.7
Operating system: [FREEBSD] amd64-portbld-freebsd7.1, compiled by GCC cc
(GCC) 4.2.1
Description: ERROR 22008 on timestamp import
Details:

Copying from a csv file (using both COPY as superuser and the psql \copy
command) fails with DATETIME FIELD OVERFLOW for values with x.9999999Z
(seven or more nines after the decimal)
'1999-08-06 05:34:10.999999643Z' and '1999-08-06 00:12:57.999999900Z' will
both fail where for example
'1999-01-12 21:08:33.991259510Z' work correctly. I am not concerned about
the rounding inherent in the datatype.

More generally, even
SELECT '1999-08-06 00:12:57.9999999Z'::timestamp with time zone; will throw
the same error, so it seems to be something in the way Postgres
rounds/truncates the field.