When using the WT_CURSOR::modify API with tables that use the WAL for durability, it's not OK to do do modify operations that aren't idempotent (can be re-applied without changing the state). Since it's possible that recovery will re-apply the operation.
Make a change that fixes that so the logging is always correct, or such operations would be disallowed.
- is related to
SERVER-44584 (3.6) Rewriting updates as modifications incorrectly considers logging state