Performance gain from reduction of GROUP BY memory allocations

In PostgreSQL Weekly News, David Fetter wrote:
> Please test the new beta.  Some of the new features are at
> http://developer.postgresql.org/docs/postgres/release.html#RELEASE-8-1

I notice that Neil's patch regarding reducing the number of memory
allocations during aggregation operations isn't mentioned. It was
originally discussed in 8.0beta (2-3?) time.

What happened there?
- patch not committed in the end
- committed but not mentioned, as a dropped item
- committed but not mentioned, since part of a larger patch

Seemed like a good performance gain to me...

I *have* tried to find this, but Neil's work on memory allocation has
been extensive... (please take the compliment...).

Best Regards, Simon Riggs