Index: wp-includes/canonical.php
===================================================================
--- wp-includes/canonical.php	(revision 21789)
+++ wp-includes/canonical.php	(working copy)
@@ -294,6 +294,7 @@
 	$redirect['query'] = preg_replace( '#^\??&*?#', '', $redirect['query'] );
 	if ( $redirect_url && !empty($redirect['query']) ) {
 		parse_str( $redirect['query'], $_parsed_query );
+		$redirect_url = str_replace( '&', '&', $redirect_url );
 		$redirect = @parse_url($redirect_url);
 
 		if ( ! empty( $_parsed_query['name'] ) && ! empty( $redirect['query'] ) ) {