The bug

When a mine cart is over a detector rail, it gets activated/turned on (this is expected), when the mine cart is removed (ie: shot with a bow, pushed, broken), the detector rail remains active/turned on.

Updating the rail does not solve the issue, one must break & replace in order for rail to return to unpowered/turned off state.

Update: This only seems to occur with the structure block, and when it loads entities from a template! Hope this is useful for debugging

How to reproduce

1. Save a structure with an activated detector rail.
2. Load the structure twice at the same place _or Load the structure, so the rail from it overwrites an existing detector rail.

Alternative repro steps:

1. Save a structure containing a minecart on a detector rail
2. Load the structure in some other place
3. Destroy the loaded minecart
4. Load the structure again, overwriting the first load
5. Destroy the loaded minecart
6. Observe the detector rail not deactivate