BUG #2144: Domain NOT NULL constraints ignored in rules

The following bug has been logged online:

Bug reference:      2144
Logged by:          John Supplee
Email address:      john@supplee.com
PostgreSQL version: 8.1.1
Operating system:   Fedore Core 4
Description:        Domain NOT NULL constraints ignored in rules
Details:

I have a database with some views which have rules for insertion.  One of
the views (view_a) inserts data into another view (view_b) with an insert
rule.  The data inserted into view_b by view_a insert rule does not have
domain NOT NULL constraints enforced.  That is, it is possible to insert a
NULL into a column whose domain forbids NULLs.  NOT NULL constraints
attached directly to columns continue to forbid NULL data in the second view
(b).

If this requires more explanation let me know.

I have observed this behavior on versions 8.0.5 and 8.1.1