Fix from #39 with test
Do not return a body for HEAD requests
Note, this happens when body is  but not undef. @miyagawa, is this the correct way to specify an empty body? - it looks like it from Plack::Response
I don't think it's correct behavior for a server to change behavior response on the request method.
If you want this behavior no matter what server, use the Head middleware (Plack::Middleware::Head).
Your test passes without the patch to .pm.
The test only fails intermittently, and the title of this pull request was not well chosen. Sorry for the confusion, I have updated the code and opened a new pull request #87.