Stopping and restarting rebalance fails

Some simple testing on Mad Hatter.

Setup was just a two node vagrant cluster on centos7.

1. configure first as data (kv) node only.

2. Load travel-sample test data ( there is another bug with that too ).

3. add second node, again as data (kv) node into cluster.

4. rebalance, stop rebalance, try and restart - fails.

Visual playback:

https://drive.google.com/open?id=1vJ--yfn5VEJzbv0HYrUg5Xg3wRVArJTI 

Logs:

[s3://cb-customers-secure/rkazak/000014/2019-08-10/collectinfo-2019-08-10t012517-ns_1@10.112.193.101.zip

s3://cb-customers-secure/rkazak/000014/2019-08-10/collectinfo-2019-08-10t012517-ns_1@10.112.193.102.zip|s3://cb-customers-secure/rkazak/000014/2019-08-10/collectinfo-2019-08-10t012517-ns_1@10.112.193.102.zip]