Plasma: Indexer swap rebalance failed with error "Timeout exceeded while awaiting headers"

Observed indexer rebalance failing with following error in logs:
Rebalance exited with reason {service_rebalance_failed,index, {rebalance_failed, {service_error, <<"Post http://127.0.0.1:9102/dropIndex: net/http: request canceled (Client.Timeout exceeded while awaiting headers)">>}}}

Note that this is observed in perf test to get swap rebalance time for 100M docs, 15k kv ops were running in background.
Without background ops rebalance completes successfully.

Job: http://perf.jenkins.couchbase.com/job/secondary-plasma-dev/160/
Logs:
https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-secondary-plasma-dev-160/172.23.98.118.zip
https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-secondary-plasma-dev-160/172.23.98.119.zip
https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-secondary-plasma-dev-160/172.23.99.118.zip
https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-secondary-plasma-dev-160/172.23.99.119.zip
https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-secondary-plasma-dev-160/172.23.99.122.zip
https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-secondary-plasma-dev-160/172.23.99.123.zip
https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-secondary-plasma-dev-160/172.23.99.241.zip
https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-secondary-plasma-dev-160/172.23.99.245.zip
https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-secondary-plasma-dev-160/172.23.99.246.zip
https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-secondary-plasma-dev-160/172.23.99.247.zip
https://s3-us-west-2.amazonaws.com/perf-artifacts/jenkins-secondary-plasma-dev-160/172.23.99.251.zip
Indexer nodes: 172.23.98.118 and 172.23.98.119