bundle2: abort when a mandatory pushkey part fails...
bundle2: abort when a mandatory pushkey part fails
So far, result of a pushkey operation had no consequence on the transaction
(beside the change). We makes it respect the 'mandatory' flag of part so that
failed pushkey call abort the whole transaction. This will allow rejecting
changes (primary target: changesets) regarding phases or bookmark criteria in
the future (when we will push such data in a mandatory part).
We currently raise an abort error because all clients support it. We'll
introduce a more precise error in the next changesets.
