Index: modules/path/path.module
===================================================================
--- modules/path/path.module
+++ modules/path/path.module
@@ -105,7 +105,7 @@
     if ($alias == drupal_get_path_alias($path, $language)) {
       // There is already such an alias, neutral or in this language.
       // Update the alias based on alias; setting the language if not yet done.
-      db_query("UPDATE {url_alias} SET src = '%s', dst = '%s', language = '%s' WHERE dst = '%s'", $path, $alias, $language, $alias);
+      db_query("UPDATE {url_alias} SET src = '%s', dst = '%s', language = '%s' WHERE dst = '%s' AND (language = '%s' OR language = '')", $path, $alias, $language, $alias, $language);
     }
     else {
       // A new alias. Add it to the database.