portupgrade failure

[Kevin]

Hello all,

I've been having this problem for a couple of months now, but I just
recently decided to try to fix it. I'm running FreeBSD 6.4, and if I
try to use portupgrade to upgrade something, I get an error (seems to
be the same for other ports):

# portupgrade -R squid
[Gathering depends for www/squid30 ./usr/local/sbin/portupgrade:878:in
`get_all_depends': private method `scan' called for #<Set: {}>
(NoMethodError)
        from /usr/local/sbin/portupgrade:871:in `get_all_depends'
        from /usr/local/lib/ruby/1.8/set.rb:195:in `each'
        from /usr/local/lib/ruby/1.8/set.rb:195:in `each_key'
        from /usr/local/lib/ruby/1.8/set.rb:195:in `each'
        from /usr/local/sbin/portupgrade:870:in `get_all_depends'
        from /usr/local/sbin/portupgrade:633:in `main'
        from /usr/local/sbin/portupgrade:607:in `each'
        from /usr/local/sbin/portupgrade:607:in `main'
        from /usr/local/sbin/portupgrade:582:in `catch'
        from /usr/local/sbin/portupgrade:582:in `main'
        from /usr/local/lib/ruby/1.8/optparse.rb:1310:in `call'
        from /usr/local/lib/ruby/1.8/optparse.rb:1310:in `parse_in_order'
        from /usr/local/lib/ruby/1.8/optparse.rb:1306:in `catch'
        from /usr/local/lib/ruby/1.8/optparse.rb:1306:in `parse_in_order'
        from /usr/local/lib/ruby/1.8/optparse.rb:1254:in `catch'
        from /usr/local/lib/ruby/1.8/optparse.rb:1254:in `parse_in_order'
        from /usr/local/lib/ruby/1.8/optparse.rb:1248:in `order!'
        from /usr/local/lib/ruby/1.8/optparse.rb:1241:in `order'
        from /usr/local/sbin/portupgrade:559:in `main'
        from /usr/local/lib/ruby/1.8/optparse.rb:791:in `initialize'
        from /usr/local/sbin/portupgrade:231:in `new'
        from /usr/local/sbin/portupgrade:231:in `main'
        from /usr/local/sbin/portupgrade:2213

The only other symptoms I can identify right now are related to the
following entries in my crontab:

0 2 * * 6       /usr/local/sbin/portsclean -DD
0 2 * * 5       /usr/local/sbin/portsclean -C

The e-mailed results simply say "env: ruby: No such file or
directory". However, these commands seem to run fine from an
interactive shell (while logged in).

I also receive the same message at the end of the output for
"/usr/sbin/portsnap cron update && /usr/local/sbin/portsdb -u >
/dev/null" run from cron:

Removing old files and directories... done.
Extracting new files:
/usr/ports/MOVED
/usr/ports/Mk/bsd.sites.mk
/usr/ports/UPDATING
<...lines deleted...>
/usr/ports/x11/9menu/
/usr/ports/x11/evilvte/
/usr/ports/x11/nvidia-driver/
Building new INDEX files... done.
env: ruby: No such file or directory

Any help would be greatly appreciated.

Thanks,
Kevin