Description
When using SPLITSHARD with async, if there are underlying failures in the SPLIT core command or other sub-commands of SPLITSHARD, then SPLITSHARD succeeds and results in two empty sub-shards.
There are various potential failures with SPLIT core command, here's a way to reproduce using a Solr 6x index in Solr 7x.
Steps to reproduce (in Solr 7x):
1. Import the attached configset, and create a collection. 2. Move in the attached data directory (index created in Solr6x) in place of the created collection's data directory. Do a collection RELOAD. 3. Issue a *:* query, we see 5 documents. 4. Issue a SPLITSHARD (async), and then issue *:*, we see 0 documents.
Check attached solr-13718-reproduce.sh script to do the same (without needing the zip file).