Index: src/wp-includes/formatting.php
===================================================================
--- src/wp-includes/formatting.php	(revision 26958)
+++ src/wp-includes/formatting.php	(working copy)
@@ -3073,7 +3073,7 @@
  * @return string Absolute path.
  */
 function wp_make_link_relative( $link ) {
-	return preg_replace( '|https?://[^/]+(/.*)|i', '$1', $link );
+	return preg_replace( '|https?://[^/]+(/?.*)|i', '$1', $link );
 }
 
 /**