Q:

Powered rail on a slope powering glitch?

I have placed a powered rail on a slope with a redstone torch underneath it as shown in the following two pictures.

Now as you can see, the powered rail is in fact unpowered, despite the redstone torch underneath it.
However, if I place a redstone torch next to the powered rail it is powered, but when I remove it, it continues to remain powered, as it should have done in the first place.

Is this a glitch? Or some behaviour of redstone/minecart tracks that I am unaware of?

A:

This is a glitch relating to the updating of blocks.
In short, the issue is that when the powered rail is placed, it does not check to see if the block it is on is already powered, but keeps its state until a nearby block updates, such as might happen when you place a redstone torch that would power it.
When that redstone torch is removed again, the track checks to see if it still powered, and, realizing that it is, stays on. (c.f. the glitch that would give free power to tracks placed on a slope when one was removed from a chain of powered rails).
Anything that causes the track to be updated should make the track powered; such as placing the tracks sequentially from bottom to top, meaning that the initial state of the powered rail will be flat: When the next rail is then placed, pulling the end of the powered track up, it updates and gets power.
Another alternative, as Dan F mentioned, is to simply place the torch after the rail.

