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Is the documentation still accurate for the 'Files' rewrite rule? It doesn't seem to be working for me, and I'm not seeing any such rules in my vhost configs with Aegir 1.9.
Finally figured this out in case anyone else runs into this issue, see - http://drupal.org/node/1791004#comment-6551456
Ultimately I figured out that the issue is ReWrite is not working on ALIASES of the site. My site is: /var/aegir/platforms/somedrupal7platform/sites/example.com (so I don't use the www prefix)
The link to
http://mysiteontheinterwebs.com/files/myfile.jpg works fine, however the link to WWW doesn't work: