Don't overwrite author name method with value

Don't overwrite author name method with value

When loading a user specific RSS feed, the funciton item_author_name got
overwritten by the name of that user. Since django doesn't recreate the
basic feed object in future requests (meh), any subsequent feed request
would get *all* authors set to that name. As long as no user-specific
feed was ever called, thing would work, but as soon as one was called it
would start moving all entries between the same users, never allowing
more than one.

The fix in a112e1e14 was clearly incomplete.