Before this fix, |dolt clone| against a sql-server remote can fail with a
confusing error message if the sql-server has a chunk journal. Adding the chunk
journal to our destination ChunkStore causes us to update the root hash, which
the Clone code was not expecting.
This change updates the Clone code to look for the possible update to the
destination's root hash and to not try to set the root hash on the ChunkStore
if it has already been done by the code handling the chunk journal.
6f646a7f01