Setting fetch URIs for portupgrade

[Andrew Terekhov]

Hi all,

I am running FreeBSD 5.1 Release. I updated all sources, ports and docs 
by cvsup. I am trying to do a binary upgrade of my system by installing 
latest packages. I run: portupgrade -aPPR. fetch phase fails to get 
packages because it goes to a wrong site: 
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5.1-release/All

OTOH I can see that the latest packages that portupgrade trying to fetch 
are located here:
ftp://ftp.freebsd.org/pub/FreeBSD/ports/i386/packages-stable/All

How can I change URIs where fetch is looking for the latest packages? 
Setting PKG_SITES environment variable doesn't have any effect. Editing 
/usr/local/etc/pkgtools.conf to set PKG_SITES also doesn't change where 
fetch is going. Handbook, man pages, googling, etc didn't find any 
references regarding how to configure fetch URIs. I don't want to 
compile everything through ports because life is short. What should I do?

Thanks a lot,
Andrew