Do not start a transaction this way.

Do not start a transaction this way.
Because we still want to commit any changes that successfully apply we
never want to do a global cancel, and because of how transaction nesting
works that means we never cancel any "transaction" at the single modify
operation level.

Let each operation start its own transaction so that the transaction is
properly canceled if any error is returned and half committed operations
(though plugins failing) are properly reverted on a per operation basis.