Consolidate set-or-default timeout code in one function

class.jetpack-network.php

@@ -401,9 +401,10 @@ public function do_subsiteregister( $site_id = null ) {
 		// Figure out what site we are working on
 		$site_id = ( is_null( $site_id ) ) ? $_GET['site_id'] : $site_id;
 
-		// Remote query timeout limit
-		$timeout = $jp->get_remote_query_timeout_limit();
-
+		// better to try (and fail) to set a higher timeout than this system
+		// supports than to have register fail for more users than it should
+		$timeout = Jetpack::set_min_time_limit( 60 ) / 2;
+
 		// The blog id on WordPress.com of the primary network site
 		$network_wpcom_blog_id = Jetpack_Options::get_option( 'id' );
 

class.jetpack.php

@@ -4776,11 +4776,25 @@ public static function delete_secrets( $action, $user_id ) {
 	 * @since 2.6
 	 * @return int
 	 **/
-	public function get_remote_query_timeout_limit() {
+	public static function get_max_execution_time() {
 	    $timeout = (int) ini_get( 'max_execution_time' );
 	    if ( ! $timeout ) // Ensure exec time set in php.ini
-				$timeout = 30;
-	    return intval( $timeout / 2 );
+			$timeout = 30;
+	    return $timeout;
+	}
+
+	/**
+	 * Sets a minimum request timeout, and returns the current timeout
+	 *
+	 * @since 5.3
+	 **/
+	public static function set_min_time_limit( $min_timeout ) {
+		$timeout = self::get_max_execution_time();
+		if ( $timeout < $min_timeout ) {
+			$timeout = $min_timeout;
+			set_time_limit( $timeout );
+		}
+		return $timeout;
 	}
 
 
@@ -4847,7 +4861,9 @@ public static function register() {
 			return new Jetpack_Error( 'missing_secrets' );
 		}
 
-		$timeout = Jetpack::init()->get_remote_query_timeout_limit();
+		// better to try (and fail) to set a higher timeout than this system
+		// supports than to have register fail for more users than it should
+		$timeout = Jetpack::set_min_time_limit( 60 ) / 2;
 
 		$gmt_offset = get_option( 'gmt_offset' );
 		if ( ! $gmt_offset ) {