update serializers

vcr/persist.py

@@ -1,30 +1,12 @@
-import tempfile
-
 from .persisters.filesystem import FilesystemPersister
 from .serialize import serialize, deserialize
 
 
-def _check_for_old_cassette(cassette_content):
-    # crate tmp with cassete content and try to migrate it
-    with tempfile.NamedTemporaryFile(mode='w+') as f:
-        f.write(cassette_content)
-        f.seek(0)
-        if migration.try_migrate(f.name):
-            raise ValueError(
-                "Your cassette files were generated in an older version "
-                "of VCR. Delete your cassettes or run the migration script."
-                "See http://git.io/mHhLBg for more details."
-            )
-
 
 def load_cassette(cassette_path, serializer):
     with open(cassette_path) as f:
         cassette_content = f.read()
-        try:
-            cassette = deserialize(cassette_content, serializer)
-        except TypeError:
-            _check_for_old_cassette(cassette_content)
-            raise
+        cassette = deserialize(cassette_content, serializer)
         return cassette