[mythtv] Unable to attach attachement in Trac?

[Jonathan Martens]

At the moment I receive this error when trying to attach a attachment to 
ticket 9316:

Oops…
Trac detected an internal error:

OSError: [Errno 13] Permission denied: '/opt/trac/mythtv/attachments/ticket'

There was an internal error in Trac. It is recommended that you notify 
your local Trac administrator with the information needed to reproduce 
the issue.

The action that triggered the error was:

POST: /attachment/ticket/9316

Kind regards,

Jonathan