HTTP/View request with blank bucket password do not work after upgrading to 5.0

Steps to Reproduce

1. Setup a Couchbase 4.6.3 1 node cluster using vagrant
2. Enable the beer-sample
3. Execute the view via CURL (This is the same http request that python uses)

   curl "http://10.111.163.101:8092/beer-sample/_design/beer/_view/brewery_beers?connection_timeout=60000&inclusive_end=true&limit=6&skip=0&stale=false"

4. Look at the bucket map via CURL (SDKs fall back to this end point)

   curl "http://h10.111.163.101:8091/pools/default/buckets/beer-sample"

5. Add a 5.0.0 node to the cluster ()
6. Execute the view via CURL against the 5.0.0 node (This is the same http request that python uses)

   curl "http://10.111.163.102:8092/beer-sample/_design/beer/_view/brewery_beers?connection_timeout=60000&inclusive_end=true&limit=6&skip=0&stale=false"

7. Look at the bucket map via CURL against the 5.0.0 node (SDKs fall back to this end point)

   curl "http://10.111.163.102:8091/pools/default/buckets/beer-sample"

8. Remove the 4.6.3 node
9. Execute the view curl again, this time it fails with 401 error.

   curl "http://10.111.163.102:8092/beer-sample/_design/beer/_view/brewery_beers?connection_timeout=60000&inclusive_end=true&limit=6&skip=0&stale=false"

10. Execute the vbucket curl again, this time it fails with 401 error.

    curl "http://10.111.163.102:8091/pools/default/buckets/beer-sample"

Problem
Breaking API change, when there was a passwordless bucket those endpoint were accessible without authentication. The python SDK does not set authentication on view request.

Expectation
For the old SDK to work during an upgrade to 5.0.0