Fixed filename too long with cache

Use sha1 digest as cache key

libs/subliminal/cache.py

@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 from __future__ import absolute_import
 import datetime
+from hashlib import sha1
 
 from dogpile.cache import make_region
 
@@ -14,4 +15,13 @@ EPISODE_EXPIRATION_TIME = datetime.timedelta(days=3).total_seconds()
 REFINER_EXPIRATION_TIME = datetime.timedelta(weeks=1).total_seconds()
 
 
-region = make_region()
+def sha1_key_mangler(key):
+    """Return sha1 hex for cache keys"""
+    if isinstance(key, str):
+        key = key.encode("utf-8")
+
+    return sha1(key).hexdigest()
+
+
+# Use key mangler to limit cache key names to 40 characters
+region = make_region(key_mangler=sha1_key_mangler)