Blocks attached to multi-block blocks are deleted when breaking the other half of the block

The bug

When breaking the half of multi-block block (e.g. doors, beds, double plants) on which a block, such as a sign, a button, or a torch, is not placed, that block will break without dropping as an item.

To reproduce

1. Place a door
2. Attach a sign (or a torch, or a button, or any other block that requires support) to one half of the door
3. Break the half of the door that you placed the block on
   → The attached block breaks and drops
4. Place the door again
5. Attach a block to the door again
6. Break the half of the door that the block was not placed on
   → The attached block breaks, but does not drop