While building a ladder to climb out of a hole, I found that my player hitbox was interfering with ladder placement while I was hanging off a ladder directly below where I wanted to build up.

I'm getting a 504 error while trying to attach a screenshot, so see:
http://i.imgur.com/TKgnTLF.png
A ladder I attempt to place with my cursor in that position jumps right back into my inventory. It will only place if I climb down a block, or hang at the far edge of the area in which I can hang on a ladder.

This placement behavior does not occur in 1.7.4 and previous. It's kind of irritating, but not game-stopping.