portupgrade upgrades ports despite +IGNOREME files

FreeBSD sequoia.int.sectornotfound.com 5.2.1-RELEASE-p9 FreeBSD 
5.2.1-RELEASE-p9 #0: Sun Jul 11 19:08:36 PDT 2004 
root_at_sequoia.int.sectornotfound.com:/usr/obj/usr/src/sys/SEQUOIA-521  i386


portupgrade upgrades ports despite +IGNOREME files.

e.g.


cd /usr/ports/lang/perl5.8/
touch "+IGNOREME"

portupgrade -Rf mail/thunderbird

===>  Building for lang/perl-5.8
[...]

Add 'lang/perl*', as a held package in /usr/local/etc/pkgtools.conf to 
no avail.

Suggestions?

BTW What I really want to do is a portupgrade -Raf in order to rebuild 
everything to fix firefox under FreeBSD 5.2.1 where it barfs on libxpcom 
symbol not found (I don't have the exact error handy), which doesn't 
occur until the libpthreads errors are resolved by adding the following 
lines to /etc/libmap.conf:

libpthread.so.1                  libc_r.so.5
libpthread.so                    libc_r.so

Without these entries, I get libpthreads.so.1 not found errors when 
starting xmms, firefox or thunderbird.

Any hints and/or help would be hugely appreciated.

-E-