Skipping unmounted datasets is confusing and not documented.

[Parakleta]

I see that a change was made in 3628f79 (and modified a few times since) to not snapshot unmounted systems, but this is confusing to me because I had explicitly set the com.sun:auto-snapshot=true flag as required by the documentation.

I have a problem now that I cannot apply recursive rules to snapshots because there are none of the relevant name on the root dataset.

Maybe if you want to preserve the existing behaviour can we have an additional flag for com.sun:auto-snapshot like force which does the snapshot even if unmounted?