[Koha] Is this a problem?

At the very end of a Koha install (git install on Ubuntu 9.04), I got the following text: chown: invalid user: 'koha:koha' make: *** [set_koha_ownsership] Error 1 I'm not sure what this is telling me or if this is a problem. Do I need to fix something or is it ok to proceed? Paul