Interesting behavior change in 8.2.x

Hi,

While inspecting a report from pgpool-II user, I found an interesting
behavior change in 8.2 series.

When connecting to 8.2.13 using 9.0's psql, I got following error
message:

11034 2010-12-27 14:50:57 JST FATAL: unrecognized configuration parameter "application_name"

However if I connect to 8.2.18, I got no such error message. This
makes pgpool-II confusing if those version of PostgreSQL are mixed
used as backend.

It seems somewhere between 8.2.13 and 8.2.18, an behavior change was
made. According to a someone who were inspecting this, the change was
precisely made between 8.2.14 and 8.2.15. I couldn't find related
item in HISTORY of 8.2.15. Does anybody know if this change was
intentional? If so, why?
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese: http://www.sraoss.co.jp