Mark broken IEs in --list-extractors

youtube_dl/__init__.py

@@ -423,7 +423,7 @@ def _real_main():
 
     if opts.list_extractors:
         for ie in extractors:
-            print(ie.IE_NAME)
+            print(ie.IE_NAME + (' (CURRENTLY BROKEN)' if not ie._WORKING else ''))
             matchedUrls = filter(lambda url: ie.suitable(url), all_urls)
             all_urls = filter(lambda url: url not in matchedUrls, all_urls)
             for mu in matchedUrls: