COUCHBASE_NUM_VBUCKETS should reject non factors of 1024

First I understand that vBuckets != 1024 is not supported (but we do have 64 vBuckets for macOS).

When exploring Eventing performance characteristics on a non-MDS one node server ( e.g. why is it slow on a single Linux node) at various vBuckets settings 1024, 512, 256, 128 and 64 - these all worked.

SELECT count cnt, type from `travel-sample` group by type

1968 airport
917 hotel
4495 landmark
24024 route
187 airline 

I then tried 340 (which is not a factor of 1024) to emulate a 3 node KV system my eventing test worked as expected BUT N1QL queries did not.   

1024/340 = 3.0117

We get wrong answers via N1QL if COUCHBASE_NUM_VBUCKETS is set to a non factor of 1024:

export COUCHBASE_NUM_VBUCKETS=340

install couchbase and setup then load `travel-sample` run these two queries

SELECT count cnt from `travel-sample`

cnt
31591

SELECT count cnt, type from `travel-sample` group by type

4 airline
18 airport
8 hotel
56 landmark
312 route
 

SELECT count cnt from `travel-sample` where type = 'hotel'

cnt
917