I'm running Roundup 1.4.15 on Ubuntu Lucid (kernel 2.6.32.16-linode28).  Backend is MySQL 5.1.  Python 2.6.5 with MySQLdb 1.2.2.

If I run in standalone mode and connect directly to the server, everything works fine.  But, if I go through a nginx proxy, 
everything works with the exception that I cannot edit any Change Notes.  Whenever I enter any text into a Change Note field, 
when I click the submit button, the server throws a "RuntimeError: response has not been started" exception.  Everything else 
works fine behind the proxy -- I can create issues, change the other fields, and so on.

I discussed this a bit on the user list.  Here's the threads, which might provide some additional details I've left out here.

http://sourceforge.net/mailarchive/forum.php?thread_name=1285799017.8311.86.camel%40santogold&forum_name=roundup-users
http://sourceforge.net/mailarchive/message.php?msg_name=1285694356.8311.28.camel%40santogold