Index: src/wp-admin/includes/user.php
===================================================================
--- src/wp-admin/includes/user.php	(revision 33611)
+++ src/wp-admin/includes/user.php	(working copy)
@@ -137,7 +137,7 @@
 		$errors->add( 'pass', __( '<strong>ERROR</strong>: Passwords may not contain the character "\\".' ), array( 'form-field' => 'pass1' ) );
 
 	/* checking the password has been typed twice the same */
-	if ( $pass1 != $pass2 )
+	if ( $pass1 != $pass2 && !( empty($pass1) || empty($pass2) ) )
 		$errors->add( 'pass', __( '<strong>ERROR</strong>: Please enter the same password in the two password fields.' ), array( 'form-field' => 'pass1' ) );
 
 	if ( !empty( $pass1 ) )