Example:
I was eploring a cave where tons were apearing out of nowhere .and discovered a dungeon with a skeleton mob spawner. I though I was pretty well armed with an iron armor set and some torches so I rushed towards the mob spawner and ignored the skeletons, after placing the torches at the spawner's side all that was left was the top, then it happened. I tapped the top side of the spawner but wasn't able to plase a torch, then skeletons kept spawning and killef me...

What I expected to happen was...:
When I tapped the top side, the torch would be places on the spawner

What actually happened was...:
Instead, it didn't happen and mobs killed me

Steps to Reproduce:
1. Find a mob spawner (which is very hard to find)
2. Try placing torches at all sides (except bottom of course)
3. Notice that you can't place a torch at the top side and get killed by all of the mobs , losing your stuff in the process and share the same fate as me...