title: Cloudfront: HTTP/2 compliance issue
body: <p>I've resorted to stackoverflow becase AWS doesn't provide technical support for free tiers.</p>
  
  <p>Someone reported an issue using httpx, the ruby HTTP client library I maintain: <a href="https://gitlab.com/honeyryderchuck/httpx/issues/64" rel="nofollow noreferrer">https://gitlab.com/honeyryderchuck/httpx/issues/64</a> </p>
  
  <p>The report came after a recent upgrade to improve HTTP/2 spec compliance in the parser. Although the library now passes the h2spec, there seem to be legitimate issues requesting from cloudfront, due to an apparent part of the spec they don't seem to comply with: when a flow control window over 2 ** 31 - 1 is advertised, the sender must not allow it and return a flow control error.</p>
  
  <p>Is it correct? </p>