resolved.
phew! so I have cluemapper up and running for the new year.
I traced the problem to a different version of subversion installed /usr/local/bin
I eventually installed mine to /opt/bin to avoid conflicts with the system subversion (so at one point I had three versions floating around).
the command doesn't specify which 'svn' to use so it gets the first one in the path which was '/usr/local/bin' not the one that cluemapper's trac wanted.
I'm stilling unravelling everything that was causing the issue, but the big thing is that the subversion in /usr/local/bin was subversion 1.4.x while everywhere else I'm working with 1.3.x.