When making a chalk mark in the same block as a replaceable block the old block is deleted without dropping.

Replication:

1. Place a torch against a wall such that the ceiling is immediately above it.
2. Make a mark with chalk on the ceiling such that it occupies the same block as the torch.
3. The torch vanishes, and the mark is made.

What should probably happen:
One of

1. The torch is dropped
2. The mark is not made and the torch remains
3. The mark and torch are both present in the block (probably difficult)

yes, definitely. I will change that. 1) sounds best

done in 2.2.1