Description:
RFC 7231 says that servers should not respond with a body to HEAD requests, but Envoy does

Repro steps:
curl -XHEAD <envoy_url> when it has no healthy upstreams, you'll see a upstream connect error or disconnect/reset before headers response body.

Note that using --head instead of -XHEAD in curl omits the response body but shows a Excess found in a non pipelined read: excess = 57 url = /foo (zero-length body) warning.

This is a minor issue but causes some surprising noise in our deploy system's logs as it performs health checks with HEAD while the service Envoy is deployed alongside is down.

Envoy version: c92a301/1.8.0-dev/Clean/RELEASE