I just thought I'd let you know that I gave you bad information. I thought I had implemented your fix as described above originally - but as I was setting up our system on a fresh server today I noticed that I had in fact not.
On a virgin fresh debian / ISPConfig 3 installation (SVN checkout) I see that you have added this fix to the SVN. However the problem is still present.
They way I had fixed it before, was commenting out the client template code entirely (the whole if(isset($params['template_master'] ... statement)
I thought I had applied your fix before - but something must have gone awry and I was still running with my old "hack"
So, FYI this is still not fixed in the SVN.