In the GoDoc of http.Response this rule is clearly described.
It is the caller's responsibility to close Body. The default HTTP client's Transport may not reuse HTTP/1.x "keep-alive" TCP connections if the Body is not read to completion and closed.
This is what reuseconn fork tries to address by verifying that the response body is consumed as well. It would be great if it was possible to incorporate such linting behaviour in bodyclose.