CoreOS took over maintaining boltbd, and a few days ago they made an offical versioned go get endpoint.
Might be worth trying.
go.etcd.io/bbolt
8 hrs ago they flipped the import: https://github.com/etcd-io/etcd/blob/e8b940f268a80c14f7082589f60cbfd3de531d12/tools/etcd-dump-db/backend.go