Networks and Sites: Allow filtering signup link redirect when a blog is not found.

This changeset applies the existing `network_site_url` filter to the signup link redirect used when the blog is not found.

Props calin, realloc, audrasjb, peterwilsoncc.
Fixes #48323.



git-svn-id: https://develop.svn.wordpress.org/trunk@62044 602fd350-edb4-49c9-b593-d223f7449a82

Author: audrasjb

src/wp-includes/ms-load.php

@@ -419,7 +419,10 @@ function ms_load_current_site_and_network( $domain, $path, $subdomain = false )
 
 		if ( $subdomain && ! defined( 'NOBLOGREDIRECT' ) ) {
 			// For a "subdomain" installation, redirect to the signup form specifically.
-			$destination .= 'wp-signup.php?new=' . str_replace( '.' . $current_site->domain, '', $domain );
+			$path = 'wp-signup.php?new=' . str_replace( '.' . $current_site->domain, '', $domain );
+
+			/** This filter is documented in wp-includes/link-template.php */
+			$destination = apply_filters( 'network_site_url', $destination . $path, $path, $scheme );
 		} elseif ( $subdomain ) {
 			/*
 			 * For a "subdomain" installation, the NOBLOGREDIRECT constant