[Blocking] Clone command block not actually changing the data inside

Release_446687
Summary:
cloned command blocks dont carry over the data of the new command properly even though it changes in the gui
Impact:
makes cloning commands impossible. Blocks Infinity Dungeon from the 1.2 store.

Repro Steps:
1. create a command block with something in it
2. clone a new command block onto that command block and note the new contents
3. power the newly cloned command

Observed Results:
note the command is still the unchanged original command
Expected Results:
the cloned command should have correctly replaced the original command

Screenshots/Videos Attached: Also attached world to reproduce.
https://youtu.be/rGAqpdWHAzM