cbbackupmgr : No. of items in the merged incremental backups not matching the src cluster

Build : 4.6.3-4047

This is from the incremental backup system tests where we run multiple iterations to generate incremental backups and merge them. The no. of items in the final merged backup do not match the no. of items in the src cluster.

i. 2 clusters. Src cluster has 3 nodes. Dest cluster has 1 node.
ii. On Src cluster, KV ops are always in progress. The KV load has a mix of creates, updates and deletes, and some documents also have expiration set.
iii. Runs 5 iterations.
iv. The following operations are performed in each iteration – rebalance out, rebalance in, failover and addback, failover and rebalance out, bucket flush.
v. An incremental backup is taken after each of these operations.
vi. At the end of the iteration, we merge the incremental backups.
vii. At the end of the test, we stop the KV ops, compact the buckets, and take one final incremental backup.
viii. Run a merge again.

At this point, there should be just 1 backup, and the number of items in that backup should match those in the src cluster. In the test, # Items on src = 16896926, # Items on dest = 15421002

The env is live for debugging. Pls let me know once done, so that we can repurpose the env.

Dest : http://54.68.177.137:8091
Src : http://52.26.27.121:8091 (Other nodes in the cluster : 34.212.221.52, 35.167.207.174)