Falling down a ledge magically beams another creature up

### Describe the bug


Testing some stuff related to hordes damaging buildings, fell down the ledge on purpose into the horde and apparently that made the zombie beam up onto the roof.

Edit: Said zombie falling down a ledge into the horde also swaps locations with another zombie.

### Steps to reproduce

1. Have a roof and a reasonably big horde of creatures below.
2. Fall down, into the horde.
3. Swap locations???

### Expected behavior

May need some more complex logic, so more zombies get pushed away to make space for the player.

### Screenshots

_No response_

### Versions and configuration

- OS: Linux
- OS Version: LSB Version: n/a; Distributor ID: Arch; Description: Arch Linux; Release: rolling; Codename: n/a;
- Game Version: 0.F-12326-gfae2b2ac65b [64-bit]
- Graphics Version: Tiles
- Game Language: System language []
- Mods loaded: [
Dark Days Ahead [dda],
Disable NPC Needs [no_npc_food],
No Fungal Growth [no_fungal_growth],
Bionic Professions [package_bionic_professions]
]

### Additional context

_No response_

The issue names no files, tests, or entry points. Start by reproducing the roof-and-horde scenario in the listed game version and observe the falling, teleporting, and location-swapping behavior. Done means falling into the horde no longer beams or swaps creatures, while the intended space-making behavior remains correct.

Written by the indexing model from the issue text.