BUG #1915: ERROR: RETURN cannot have a parameter in function returning void at or near "NULL" at character 148

The following bug has been logged online:

Bug reference: 1915
Logged by: Roy Wood
Email address: roy.wood@clearswift.com
PostgreSQL version: 8.1-beta2
Operating system: Win32
Description: ERROR: RETURN cannot have a parameter in function
returning void at or near "NULL" at character 148
Details:

Obtained this error creating a Function which contained 'RETURN NULL;' on
the new 8.1-beta2

This error did not occur on 8.0.2 previously

ERROR: RETURN cannot have a parameter in function returning void at or near
"NULL" at character 1488

Has something changed ... as validation was not previously picking this up
as an error?