The Bug

A redstone block or redstone torch won't change the direction of a rail unless it is underneath it as shown in the 1st screenshot.

Steps to prove that this is a bug:

1. (see screenshots 2-5)
2. Place a line of 3 parallel rails
3. Place 1 rail perpendicular to the line to make a T-shape
4. Place a redstone block next to the middle rail, then remove it

Expected Result

The Rail would change its orientation

Observed Result

Upon removing the redstone block, the middle rail will update and turn into a corner rail. So it is clearly affected by redstone blocks, just not in the correct way.