LWW drift_ahead_threshold_exceeded count set for the wrong vbucket

This is observed with build 4.6.0-3404.

The test case does:

1. Create an LWW bucket
2. Set with meta where the HLC is the sum of the HLC of a recent mutation and the ahead threshold multiplied by 50
3. Check the vbucket-details for the vbucket for the key and the ahead threshold is 0, 1 is expected.

But the ahead threshold for vbucket 0 is 1, it seems like count is applied to the wrong vbucket.

The test runner command is:

./testrunner -i 1node.ini  -t epengine.lww_stats.LWWStatsTests.test_drift_stats,vbuckets=1024,conflict_resolution=lww

And 1node.ini should look like:

[global]

username:root

password:couchbase

port:8091

[membase]

rest_username:Administrator

rest_password:password

[servers]

1:_1

[_1]

ip:server-ip-here

services:kv,index,n1ql