Add filter for developers testing downloads from local servers

[afragen]

I can be the only one.

I have set up a local git server that runs on my LAN, 192.168.x.x

I use it to test plugin/theme updating. Within wp-includes/http.php wp_http_validate_url() we can already use the filter hook http_request_host_is_external, however, at the end of the function is a conditional test that will still fail and not return the $url. This is because $same_host is false if the dev environment and the local git server aren't on the same host/IP.

if ( $parsed_home && $same_host && isset( $parsed_home['port'] ) && $parsed_home['port'] === $port {
		return $url;
	}

My patch is a filter in a new conditional just after this penultimate conditional.

[afragen]

I found another way around by filtering 'http_request_args'. Sorry I was premature.