Problems with cvs from cvs-repository

[Stephen Montgomery-Smith]

I see that a lot of RELENG_9 tags have been created in the last day or 
so.  So I thought I would get the sources in the following manner:

I downloaded the complete cvs repository using cvsup.  Then I ran the 
commands
env CVSROOT=/whereever-it-is/cvs cvs co -rRELENG_9 src
and nothing happened except the directory src was created.

However if I try cvsup with RELENG_9, it works just fine.

Is this something to do with svn to cvs conversion, and somehow 
something isn't set quite right?  Or did I completely mess up the commands?