Incremental hung for 100 doc group and 1000 index test

The last good build is 7.1.0-2123 
Test:  Incremental index (min), 1 bucket x 50M x 1KB, 100 doc groups, 1000 indexes, 100K KV ops/sec, no mutations during initial build only, MOI

http://showfast.sc.couchbase.com/#/timeline/Linux/secondary/incremental/MOI#secondary_50M_1000_indexes_default_baseline_moi_incremental_hemera 

It's a baseline test we run once in a while. We are seeing that incremental index build not even getting completed in 8hrs. 

Test run : http://perf.jenkins.couchbase.com/job/aether/1681/console