fix reading sd blob

TODO: add __enter__ and __exit__ methods to HashBlobReader to let it be
used as a contextmanager

lbrynet/blob/reader.py

@@ -33,6 +33,7 @@ class HashBlobReader_v0(object):
         if self.streaming is False:
             reactor.callLater(0, self.producer.resumeProducing)
 
+
 class HashBlobReader(object):
     """
     This is a file like reader class that supports

lbrynet/reflector/server/server.py

@@ -331,8 +331,9 @@ class ReflectorServer(Protocol):
         return d
 
     def determine_missing_blobs(self, sd_blob):
-        with sd_blob.open_for_reading() as sd_file:
-            sd_blob_data = sd_file.read()
+        reader = sd_blob.open_for_reading()
+        sd_blob_data = reader.read()
+        reader.close()
         decoded_sd_blob = json.loads(sd_blob_data)
         return self.get_unvalidated_blobs_in_stream(decoded_sd_blob)