a888c4091c
This adds a "dry-run" / "pre-check" option for prune-functions, which delegates constructing the confirmation message (what is about to be pruned) and validation of the given options to the prune-functions. This helps separating concerns, and doesn't enforce knowledge about what's supported by each content-type onto the system prune command. Signed-off-by: Sebastiaan van Stijn <github@gone.nl>