Master should handle the case where the REPLICATE fails (which I discovered when running a transaction against a non-leader case) in SysTables.
This is a bit tricky as for master we update the in-memory tables first, then commit the transaction.
Only way would be able to do the following:
Under the lock for the appropriate CopyOnWrite object--
1) Save the old version of the object.
2) Make the appropriate modification.
3) If REPLICATE fails, go back to the old version.