Index: wp-admin/customize.php
===================================================================
--- wp-admin/customize.php	(revision 28441)
+++ wp-admin/customize.php	(working copy)
@@ -18,10 +18,11 @@
 wp_reset_vars( array( 'url', 'return' ) );
 $url = urldecode( $url );
 $url = wp_validate_redirect( $url, home_url( '/' ) );
-if ( $return )
+if ( $return ) {
 	$return = wp_validate_redirect( urldecode( $return ) );
-if ( ! $return )
+} else {
 	$return = $url;
+}
 
 global $wp_scripts, $wp_customize;