This commit in v6.0 introduced the _shardsvrSplitChunk and _shardsvrMergeChunks aliases for the split and merge commands on shards in order to differentiate them from the router ones (merge and split). The aliasing was needed in order to get rid of the non-shardsvr command names in a future version because shiwtching right away the router to call into _shardsvr* commands would have resulted in breaking backwards compatibility with v5.0.

Being already in v8.1, it is now possible to proceed as follows:

• Change the router commands to always invoke the _shardsvr* commands since both v8.0 and future versions "understand" it
• Fill in a ticket to get rid of the merge and split aliases in v9.1 (v9.0 will still has to "understand" the old command name because v8.0 routers were not invoking yet the _shardsvr* commands).