Issue with conditional operations and verisioning

The problem:

• repeatable read cache with write skew check enabled
• a conditional operation (e.g. replace) executes and is not successful (e.g. because the value doesn't exist)
• during the successful operation the entry is written to the container with a null version. (i.e. the previous version is erased). That is well bad!

Suggested solution:

• for such entries that were not modified (isChanged==false) the value should not be re-written to the container OR

Attached is a unit test capturing the problem.