Index: includes/locale.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/locale.inc,v
retrieving revision 1.174.2.10
diff -u -p -r1.174.2.10 locale.inc
--- includes/locale.inc	15 Sep 2009 10:40:26 -0000	1.174.2.10
+++ includes/locale.inc	18 Dec 2009 10:06:32 -0000
@@ -2166,6 +2166,7 @@ function _locale_rebuild_js($langcode = 
   }
 
   // Construct the JavaScript file, if there are translations.
+  $data_hash = NULL;
   $data = $status = '';
   if (!empty($translations)) {
 
@@ -2184,22 +2185,38 @@ function _locale_rebuild_js($langcode = 
   $dir = file_create_path(variable_get('locale_js_directory', 'languages'));
 
   // Delete old file, if we have no translations anymore, or a different file to be saved.
-  if (!empty($language->javascript) && (!$data || $language->javascript != $data_hash)) {
+  $changed_hash = $language->javascript != $data_hash;
+  if (!empty($language->javascript) && (!$data || $changed_hash)) {
     file_delete(file_create_path($dir .'/'. $language->language .'_'. $language->javascript .'.js'));
     $language->javascript = '';
     $status = 'deleted';
   }
 
-  // Only create a new file if the content has changed.
-  if ($data && $language->javascript != $data_hash) {
+  // Only create a new file if the content has changed or the original file got
+  // lost.
+  $dest = $dir .'/'. $language->language .'_'. $data_hash .'.js';
+  if ($data && ($changed_hash || !file_exists($dest))) {
     // Ensure that the directory exists and is writable, if possible.
     file_check_directory($dir, TRUE);
 
     // Save the file.
-    $dest = $dir .'/'. $language->language .'_'. $data_hash .'.js';
     if (file_save_data($data, $dest)) {
       $language->javascript = $data_hash;
-      $status = ($status == 'deleted') ? 'updated' : 'created';
+      // If we deleted a previous version of the file and we replace it with a
+      // new one we have an update.
+      if ($status == 'deleted') {
+        $status = 'updated';
+      }
+      // If the file did not exist previously and the data has has changed we
+      // have a fresh creation.
+      elseif ($changed_hash) {
+        $status = 'created';
+      }
+      // If the data hash is unchanged the translation was lost and has to be
+      // rebuilt.
+      else {
+        $status = 'rebuilt';
+      }
     }
     else {
       $language->javascript = '';
@@ -2207,9 +2224,10 @@ function _locale_rebuild_js($langcode = 
     }
   }
 
-  // Save the new JavaScript hash (or an empty value if the file
-  // just got deleted). Act only if some operation was executed.
-  if ($status) {
+  // Save the new JavaScript hash (or an empty value if the file just got
+  // deleted). Act only if some operation was executed that changed the hash
+  // code.
+  if ($status && $changed_hash) {
     db_query("UPDATE {languages} SET javascript = '%s' WHERE language = '%s'", $language->javascript, $language->language);
 
     // Update the default language variable if the default language has been altered.
@@ -2227,6 +2245,10 @@ function _locale_rebuild_js($langcode = 
     case 'updated':
       watchdog('locale', 'Updated JavaScript translation file for the language %language.', array('%language' => t($language->name)));
       return TRUE;
+    case 'rebuilt':
+      watchdog('locale', 'JavaScript translation file %file.js was lost.', array('%file' => $language->javascript), WATCHDOG_WARNING);
+      // Proceed to the 'created' case as the JavaScript translation file has
+      // been created again.
     case 'created':
       watchdog('locale', 'Created JavaScript translation file for the language %language.', array('%language' => t($language->name)));
       return TRUE;