incorrect error message when connstr is missing bucket

I suspect this is an artifact of defaulting to defaults, but note that if I do not have a bucket name on the connstr, cbc says authentication fails:

$ cbc stats key -U couchbase://centos7lx-55a.home.ingenthron.org -u bench -P -  green::1::10001874

Bucket password: 

Failed to bootstrap instance. libcouchbase error: Authentication failed. You may have provided an invalid username/password combination (0x2)

The cluster log indicates the auth was successful, but it probably failed at bucket select because I left out the bucket name from the connstr. Would be great to make the error associated with the actual failure.