OK^2, now we've really got this figured out :-)

This is fundamentally a file-system permissions problem.  The reason it 
only affected Change Notes is because a change note ends up being 
written out to a "msg" file on the file system.  When running in 
standalone mode (started by init.d), the python process was running as 
root.  When running under apache with mod_wsgi, it was running as www-
data and didn't have write permission on the msg directory.

The X-Forward-For stuff was an entirely different problem, which just 
added confusion to the analysis.