rust-clippy: apply some more trivial fixes All of these were hinted at by clippy and make the code simpler.

rust-clippy: simplify `match` to `if let` This was hinted at by clippy, and makes it more obvious that nothing is happening in the `None` case.

censor: accept multiple revision in a single call This is useful when dealing with corruption, as all the corrupted revision can be dealt with in one go.

censor: be more verbose about the other steps too If we informs the user about head checking, we should tell him when the other operation happens too. Otherwise the user can imagine to still be in the head checking part.