Empty cache when ValueError is raised with 'unsupported pickle protocol: 3'. This happen when cache have been pickled with Python3 but is read by Python2.

bazarr/get_providers.py

@@ -10,6 +10,7 @@ from get_args import args
 from config import settings
 from subliminal_patch.exceptions import TooManyRequests, APIThrottled, ParseResponseError
 from subliminal.exceptions import DownloadLimitExceeded, ServiceUnavailable
+from subliminal import region as subliminal_cache_region
 
 VALID_THROTTLE_EXCEPTIONS = (TooManyRequests, DownloadLimitExceeded, ServiceUnavailable, APIThrottled,
                              ParseResponseError)
@@ -154,6 +155,13 @@ def provider_throttle(name, exception):
     throttle_until = datetime.datetime.now() + throttle_delta
     
     if cls_name not in VALID_COUNT_EXCEPTIONS or throttled_count(name):
+        if cls_name == 'ValueError' and exception.message.startswith('unsupported pickle protocol'):
+            for fn in subliminal_cache_region.backend.all_filenames:
+                try:
+                    os.remove(fn)
+                except (IOError, OSError):
+                    logging.debug("Couldn't remove cache file: %s", os.path.basename(fn))
+        else:
             tp[name] = (cls_name, throttle_until, throttle_description)
             settings.general.throtteled_providers = str(tp)
             with open(os.path.join(args.config_dir, 'config', 'config.ini'), 'w+') as handle: