Rebuilding caches does not force a javascript translation file rebuild

Due too some circumstances the javascript language file got lost. I was unable to force drupal to rebuild the file, because drupal checks if the hash of the contents recreated in memory and the hash in the database are still the same. It doesn't check if the file exists or not.

What I had to do was:
- manually edit the javascript field in the languages table to something else
- change the default language to english and back to update the variable
- run the rebuild cache functionality

I think that the rebuild cache functionality should always rebuild the javascript file, or at least check if it has been deleted.