`run-before` scripts will not run if the source paths are not present?

If the sources are not present the `run-before` hook would not run at all. This kills use cases like using `run-before` hook to trigger fs snapshots creation.

https://github.com/rustic-rs/rustic/blob/852635e25c39b5ccd9f4c7b6bc544cc3f9a2f453/src/commands/backup.rs#L187