Location headers on proxy POSTs badly mangle response.

[dcporter]

Along with being used in "content moved" responses, Location headers are often returned by RESTful APIs when content is successfully created via POST. Somewhere (though not in the proxy-handling method), abbot is apparently misunderstanding this Location header to be a "content moved" one, and re-POSTing to the new location. Then it's apparently appending the headers from the second response into the body of the first response, which is generally useless.