Summary

_mongoc_cmd_parts_ensure_copied() is typically called from mongoc_cmd_parts_assemble() before appending common command options (e.g. lsid, read/write concern). It notably is not called before appending Stable API options.

I'm not sure if this is an intentional decision or an oversight. In practice, this may not affect any users as it's likely the command parts will already have been copied due to an earlier append.