final StoredConfig config = db2.getConfig();
RemoteConfig remoteConfig = new RemoteConfig(config, "origin");
URIish uri = new URIish(db.getDirectory().toURI().toURL());
remoteConfig.addURI(uri);
remoteConfig.update(config);
config.save();
// fetch from first repository
RefSpec spec = new RefSpec("+refs/heads/*:refs/remotes/origin/*");
git2.fetch().setRemote("origin").setRefSpecs(spec).call();
return db2;