autoconf trouble in the CVS HEAD

I found a tiny fix for configure.in at Nov 26.

http://developer.postgresql.org/cvsweb.cgi/pgsql/configure.in.diff?r1=1.537;r2=1.538;f=h

It seems to me this check enforces us to use autoconf 2.59, not the latest one.
Is there any reason for this change?

For example, autoconf 2.61 is installed in the Fedora 7, 8 and rawhide,
so this chage will be troubled for many developers.

Thanks,
-- 
OSS Platform Development Division, NEC
KaiGai Kohei <kaigai@ak.jp.nec.com>