Host header processing

[frumioj]

Noting this code from AWS Signer v4 code:

if port != "" && isDefaultPort(r.URL.Scheme, port) {
		r.Host = stripPort(host)
}

What this means is that if I get a Host of localhost:8080 for example, the port will NOT be stripped for AWS Golang SDK. However, I note that in the curl implementation, they do strip the port in this case (and perhaps others). I see nothing in Creating a Signed Request about this, so it's not clear to me whether the port should be stripped or not, and what the rationale is. This makes me question whether the writer of this code actually just forgot to put !isDefaultPort in the above code?