Cannot install per README instructions

$ go get gopkg.in/couchbaselabs/gocb.v0

1. gopkg.in/couchbaselabs/gocb.v0
   ../../../gopkg.in/couchbaselabs/gocb.v0/bucket_crud.go:123: cannot convert cb (type ioCasCallback) to type gocbcore.UnlockCallback
   ../../../gopkg.in/couchbaselabs/gocb.v0/bucket_crud.go:139: cannot convert cb (type ioCasCallback) to type gocbcore.TouchCallback
   ../../../gopkg.in/couchbaselabs/gocb.v0/bucket_crud.go:147: cannot convert cb (type ioCasCallback) to type gocbcore.RemoveCallback
   ../../../gopkg.in/couchbaselabs/gocb.v0/bucket_crud.go:160: cannot convert cb (type ioCasCallback) to type gocbcore.StoreCallback
   ../../../gopkg.in/couchbaselabs/gocb.v0/bucket_crud.go:173: cannot convert cb (type ioCasCallback) to type gocbcore.StoreCallback
   ../../../gopkg.in/couchbaselabs/gocb.v0/bucket_crud.go:186: cannot convert cb (type ioCasCallback) to type gocbcore.StoreCallback
   ../../../gopkg.in/couchbaselabs/gocb.v0/bucket_crud.go:194: cannot convert cb (type ioCasCallback) to type gocbcore.StoreCallback
   ../../../gopkg.in/couchbaselabs/gocb.v0/bucket_crud.go:202: cannot convert cb (type ioCasCallback) to type gocbcore.StoreCallback
   ../../../gopkg.in/couchbaselabs/gocb.v0/bucket_crud.go:216: cannot convert cb (type ioCtrCallback) to type gocbcore.CounterCallback
   ../../../gopkg.in/couchbaselabs/gocb.v0/bucket_crud.go:221: cannot convert cb (type ioCtrCallback) to type gocbcore.CounterCallback
   ../../../gopkg.in/couchbaselabs/gocb.v0/bucket_crud.go:221: too many errors

OTOH, this worked:

$ go get -u -v github.com/couchbase/gocb
github.com/couchbase/gocb (download)
github.com/couchbase/gocb/gocbcore
github.com/couchbase/gocb