filemap[file][verID+".json"] = buf.String()
					}
					return nil
				})
				if err != nil {
					return nil, err
				}
				enc := json.NewEncoder(buf)
				if err := enc.Encode(struct {
					Versions []version
				}{Versions: versions}); err != nil {
					return nil, err
				}
				data = b
			default:
				return nil, fmt.Errorf("unknown metadata version %d", minor)
			}