Broken leads will drop item with doEntityDrops set to false
Reproduction:
- Create a new superflat world with creative and cheats.
- Disable entity drops (/gamerule doEntityDrops false)
- Spawn a pig and a fence.
- Attach the pig to the fence.
- Break the fence.
- The lead will drop.
Observations:
Itemframes will not drop the item when you remove the supporting block.
However, the lead will drop when you break the fence.
Conclusion:
Clearly this is unintended.