Cluster.OpenBucket() API hangs when connecting to non-existent bucket against Spock

I'm noticing a difference in behavior when calling Cluster.OpenBucket() on a non-existent bucket on Couchbase 5.x (5.0.0 build 2873) vs 4.x (4.1.0-5005).  

In the 5.x case, it just seems to hang forever, whereas in the 4.x case I get an error back immediately.

Steps to repro:

• Couchbase server 5.0.0 build 2873 running under Virtualbox.  (admin user is username: Administrator password: password)
• Delete default bucket so there aren't any buckets
• GoCB commit d5a64dd7982b3c07cb0675e995e249fa58cd92ff
• Create RBAC user with username=testbucket password=password
• Run this code to open the non-existent bucket named "testbucket": https://gist.github.com/tleyden/5501e4e12c25487ed10baae37a731417

Actual behavior:

The call to Cluster.OpenBucket() blocks indefinitely, here are the logs: https://gist.github.com/tleyden/46c7ca77c8df71ca59781cb58018eada

Expected behavior:

On Couchbase 4.x, it returns an error immediately, here are the logs:

https://gist.github.com/tleyden/eafd0230b516c8e948fe9fbfa9a36ed9