This bug involves placing a torch on a wall where two blocks meet in a corner. I'll try placing a torch, and it appears on the other block.
Here's what I found step-by-step:
1. Placed four blocks together on a flat surface with a hole in the middle (X = any block)
[ ] [X] [ ]
[X] [ ] [X]
[ ] [X] [ ]
2. Placed a torch inside the hole, facing north (according to the clouds, which I've heard move west). i = torch
[ ] [X] [ ]
[X] [i] [X]
[ ] [X] [ ]
In this step I've found that the placed torch instead is placed on the block facing west, not the one I'm facing.
Altogether, you can't place torches on the North and South sides of a corner on any surface. Exceptions are when corners come to a point at NE and SE, in which the torch will be placed on the East wall in both instances. Lastly, in tunnels 1-block in width going straight from east to west, placing a torch will always go on the north side.
This is an annoying bug to have to get around, as I have to remove the block it is biased to being placed on in order to put a torch where I want, and then place that block back. Please fix.