MD works in unequipped sling strap

## Testmerges
#7703: 'Hivelord Strain: Designer [Ver. 0.9]' by Venuska1117 at commit 716057dd1f
#7023: 'Research Rework Part Two: The Contract System.' by kiVts at commit dd2764717f
#7242: 'WIP Yautja Clan TGUI Menu' by realforest2001 at commit ba93dc064c
#9040: 'New In_hands and On_mobs (IDs, Backpacks, Belts, Swords and Knives)' by LC4492 at commit 9b891563ab
#9034: 'lurker rework, Pounce changes, invis decreased on pounce/damage' by private-tristan at commit 0d19f411d3
#9274: 'introduces two factor authentication for admins' by hry-gh at commit 5e1e054f88

## Round ID
27824

## Description of the bug
If you slap an MD into the sling strap and unequip the strap and leave it on the floor, MD would work

## What's the difference with what should have happened?
It should normally turn off as if discarded?

## How do we reproduce this bug?
1) Put a Motion Detector into a sling strap (pouch attachment)
2) Turn the MD on
3) Insert it back into the sling strap (not drop for auto pickup)
4) Drop the sling pouch

## Attached logs
```
N/A
```

## Additional details
- Author: BlackSwanny
- Admin: Piterskiy
- Note: None