Fix CI artifacts not uploading with tracing enabled and without NGINX
Labkit::Tracing::RackMiddleware will attempt to sanitize the
parameters using Rails' ActionDispatch::Http::FilterParameters. However, if it is run before
Rack gets a chance to read and parse a multipart message AND no Content-Length is set, no multipart data will be present.
FilterParameters works by reading the entire HTTP request by calling
the Rack POST method. However, if a chunked transfer is used, the HTTP
Content-Length header will not be defined, but
ActionDispatch::Request will always return a content length of 0
instead of nil. As a result, Rack::Multipart::Parser will be fooled
into thinking that there is no body to parse, and uploads that depend on
multipart data will fail.
To fix this, we put Rack::MethodOverride before the
Tracing::RackMiddleware to ensure that the multipart messages are
parsed by Rack first. Unlike Rails' ActionDispatch::Request,
Rack::Request treats an undefined Content-Length header as a nil
value.
Note that if NGINX or some other reverse proxy is used, the
Content-Length header should be present, so the problem described above
only affects installations that don't buffer the request.