Entities are not forced out when the space they are in is filled around path blocks.

1. Find or make 2 adjacent and level path blocks.
2. Dig out the one of the path blocks such that the block entity remains in the hole you just dug or just throw in your diamond fortune 3 pickaxe.
3. Stand back and fill in the hole with a piece of dirt.
4. Marvel as your items do not rise to the surface (and don't worry about that pickaxe; it is useless anyways).
5. Dig out the hole again to retrieve items.
6. Continue enjoying the beta.