HEAD responses include body

[titanous]

RFC 2616 section 9.4 states:

The HEAD method is identical to GET except that the server MUST NOT return a message-body in the response.

A HEAD request against this simple Rack app running on puma version 2.0.1:

require 'rack'

run lambda { |env| [200, {}, ['test']] }

looks like this on the wire:

HEAD / HTTP/1.1
User-Agent: curl/7.24.0 (x86_64-apple-darwin12.0) libcurl/7.24.0 OpenSSL/0.9.8x zlib/1.2.5
Host: localhost:9292
Accept: */*

HTTP/1.1 200 OK
Transfer-Encoding: chunked

4
test
0

Even stranger, the body [''] looks like this:

HTTP/1.1 200 OK
Transfer-Encoding: chunked

0

0

And []:

HTTP/1.1 200 OK
Transfer-Encoding: chunked

0

[titanous]

Related: rack/rack#574.