Small patch for the markup validator

Hi,

I fixed a bug that was occurring when the markup validator was reporting 
a critical errors with the unicorn output. The patch is very simple, it 
only adds 3 lines in the perl script and a template file 
(ucn_fault.tmpl) [1].
Everything is already in Mercurial, and I applied the changes on the 
validator.w3.org as this bug was impacting a lot of users.
Now I wonder if we should make a minor bug fix release.

What do you think?

[1] http://dvcs.w3.org/hg/markup-validator/rev/c0ccb44a88a1

Thanks,
Jean-Gui