I was trying to make a storage mine cart loading/unloading system when I realized that comparators are only powered by filled storage chests if they are on detector rails. The powered rail is essential for stopping/starting the mine cart for loading/unloading. The mine cart on a detector rail will not even take items from a hopper (due to the detector rail powering the hopper).

What I expected to happen was...:
When a storage mine cart holds items, it powers an adjacent comparator, no matter what rail it is on.

What actually happened was...:
Instead, a filled storage mine cart will only power an adjacent comparator if it is on a detector rail.

Steps to Reproduce:
1. Place a storage mine cart with items on a powered/activator/normal rail.
2. Place a comparator next to the rail.
3. Notice that there is no output from the comparator.