FTS index build gets stuck with gocbcore@9.1.3

Build : 7.0.0-4708
Last known good build : 7.0.0-4706

Steps to repro :
1. 1 node cluster with kv, index, query, search services
2. Install beer-sample bucket
3. Create an FTS index with default mapping with 6 partitions.

Indexing gets stuck with 7156 docs at 97.99%. See screenshot.

Changelog between the builds : http://changelog.build.couchbase.com/?product=couchbase-server&fromVersion=7.0.0&fromBuild=4706&toVersion=7.0.0&toBuild=4708&f_cbft=on&f_cbftx=on&f_cbgt=on&f_kv_engine=on&f_n1fty=on&f_ns_server=on&f_plasma=on&f_product-metadata=on&f_query=on&f_testrunner=on

Logs : https://cb-jira.s3.us-east-2.amazonaws.com/logs/fts_idx_stuck/collectinfo-2021-03-18T222546-ns_1%40127.0.0.1.zip