Coding Standards: Use strict comparison in `wpmu_signup_blog_notifica…

…tion()`.

Follow-up to [https://mu.trac.wordpress.org/changeset/1970 mu:1970].

Props debarghyabanerjee.
See #62283.

git-svn-id: https://develop.svn.wordpress.org/trunk@59560 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/ms-functions.php

@@ -941,7 +941,7 @@ function wpmu_signup_blog_notification( $domain, $path, $title, $user_login, $us
 	}
 
 	// Send email with activation link.
-	if ( ! is_subdomain_install() || get_current_network_id() != 1 ) {
+	if ( ! is_subdomain_install() || get_current_network_id() !== 1 ) {
 		$activate_url = network_site_url( "wp-activate.php?key=$key" );
 	} else {
 		$activate_url = "http://{$domain}{$path}wp-activate.php?key=$key"; // @todo Use *_url() API.