With request_buffers or response_buffers set to unlimited, the error
from reading the body was discarded and whatever had been read was
treated as the complete body. A request cut short by request_body
max_size was forwarded truncated with a 200, and a truncated chunked
upstream response was sent to the client as complete.
Handle a read error the same way the limited case already does.
Jay Hemnani
fc3d83400b