A consistency of split shard bug in v7.3.1-release
I have a collection1 with 8 shards，each shard‘s replicationFactor=1.
I have an application adding 6000w document with infinite retry if any
That is to say, finally it should be found 6000w docs when query=*:*.
Normally, all things good, but if in the same time, a SPLIT SHARD
request happen concurrently,
it would get numFound < 6000w docs finally。
I found that if sub shard in "active" status，it would throws exception
“*Request says it is coming from parent shard leader but we are in active
state*” ， but parent shard do not throws this exception to client，so client
do treat this request as SUCCESS。
I write a UT and can reproduce this Exception. Any one know why？