Fix in bitseq.NewHandle()

- When creating the handle, write it to store if
  not present. Currently it is written to store
  only on first bit allocation.

Signed-off-by: Alessandro Boch <aboch@docker.com>

libnetwork/bitseq/sequence.go

@@ -65,6 +65,13 @@ func NewHandle(app string, ds datastore.DataStore, id string, numElements uint32
 		return nil, err
 	}
 
+	// If the handle is not in store, write it.
+	if !h.Exists() {
+		if err := h.writeToStore(); err != nil {
+			return nil, fmt.Errorf("failed to write bitsequence to store: %v", err)
+		}
+	}
+
 	return h, nil
 }