The bug
Both types of torches (torch and redstone_torch) can be placed on the side of blocks that do not have a side that touches the torch
Affected blocks:
banners
buttons
levers
pressure plates
rails
redstone dust
signs
tripwire
tripwire hook
Steps to repeat
Place down one of the blocks listed above
Either shift+right-click against the hitbox of the block while holding a torch, or attempt to place a torch on top of a non-viable block (such as a slab) diagonally under the block placed in step 1
Linked issues
duplicates 1
Attachments
Comments 3

Confirmed for nether portal blocks too (when shift clicking)
Resolving as duplicate of MC-115805, highly likely the same cause and fix.
Can confirm