sand/gravel doesn't break properly when landing on sugar cane/mushroom

Steps to reproduce

• Build a little tower with a 2 or more block tall stalk of sugar cane
• Observe the sand

It will only break when it reaches the bottom of the stalk, even though the sugar cane should be breaking.

• Make the sand land on a mushroom this time
• Observe the sand

It will break, although it should really be the mushroom which breaks