[System Test][6.0.4]Found recs_on_disk to be having negative value (u'default:default_result:recs_on_disk', -909)

Build : 6.0.4-3070
Test: -test tests/2i/test_idx_rebalance_replica_vulcan_kv_opt.yml -scope tests/2i/scope_idx_rebalance_replica_vulcan.yml
Scale: 2

Found recs_on_disk to be having negative value:

172.23.104.25 : index
stats/storage : None
stats : [(u'default:default_result:recs_on_disk', -909), (u'other-3:o3_result_rating:recs_on_disk', -916), (u'other-1:o1_result_rating (replica 1):recs_on_disk', -58203), (u'default:default_result_ratings_claims_pindex (replica 1):recs_on_disk', -151)]

cluster spec:

index : 3 ===== > [172.23.104.23:8091 172.23.104.25:8091 172.23.96.96:8091]
kv : 3 ===== > [172.23.104.16:8091 172.23.104.17:8091 172.23.104.18:8091]
n1ql : 2 ===== > [172.23.104.19:8091 172.23.104.21:8091]

cbcollect logs:

url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1579257689/collectinfo-2020-01-17T104131-ns_1%40172.23.104.18.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1579257689/collectinfo-2020-01-17T104131-ns_1%40172.23.104.19.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1579257689/collectinfo-2020-01-17T104131-ns_1%40172.23.104.21.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1579257689/collectinfo-2020-01-17T104131-ns_1%40172.23.104.23.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1579257689/collectinfo-2020-01-17T104131-ns_1%40172.23.96.96.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1579257689/collectinfo-2020-01-17T104131-ns_1%40172.23.104.16.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1579257689/collectinfo-2020-01-17T104131-ns_1%40172.23.104.17.zip
url : https://cb-jira.s3.us-east-2.amazonaws.com/logs/systestmon-1579257689/collectinfo-2020-01-17T104131-ns_1%40172.23.104.25.zip