rg3/youtube-dl — pull request #764 by jaimeMF (2013-03-30 13:15:47+00:00)
Title: Fix crash when subtitles are not found

Should fix #753
`_extract_subtitle` was expected to return a list with a tuple `[(error_message, sub_lang, sub)]`, but it returned a tuple like: `(error_message, None)`.
One question, those are errors or warnings, should the program continues or stops?