pg_upgrade from 9.0 to 9.1

Hiya

running lucid 64 bit. When I try to start pg_upgrade I get the following
output:

postgres(at)newcollab:/tmp$ /usr/lib/postgresql/9.1/bin/pg_upgrade -b
/usr/lib/postgresql/9.0/bin -B /usr/lib/postgresql/9.1/bin
-d/var/lib/postgresql/9.0/main -D /var/lib/postgresql/9.1/main
Performing Consistency Checks
-----------------------------
Checking current, bin, and data directories ok
Checking cluster versions ok

and after this nothing. top shows pg_config running at a solid 20% CPU,
ps gives the following output:

$ps aux | grep postg
postgres 15559 0.0 0.0 89660 2628 pts/0 S 19:39 0:00 su postgres
postgres 15560 0.0 0.0 11164 1964 pts/0 S 19:39 0:00 bash
postgres 21385 0.0 0.0 50600 2252 pts/0 S+ 19:48 0:00
/usr/lib/postgresql/9.1/bin/pg_upgrade -b /usr/lib/postgresql/9.0/bin -B
/usr/lib/postgresql/9.1/bin -d/var/lib/postgresql/9.0/main -D
/var/lib/postgresql/9.1/main
postgres 21390 0.0 0.0 4096 572 pts/0 S+ 19:48 0:00 sh -c
"/usr/lib/postgresql/9.1/bin/pg_config" --pkglibdir
postgres 21391 20.1 0.0 4096 576 pts/0 S+ 19:48 0:10 /bin/sh
/usr/lib/postgresql/9.1/bin/pg_config --pkglibdir

so far I have broken off after about 5 minutes. Has anybody seen this
behaviour before?

Thanks!

Bernhard