Taking damage from falling into things, despite being suspended above them by a cobweb

Taking damage from falling into things despite being suspended above them by a cobweb (that really wasn't concise, sorry).

Steps to Reproduce:
Place cobweb(s) above something deadly, e.g. lava, below the world, a deadly drop
In Survival, stand in the cobweb above this.

Observed Results:
Took fall damage, caught fire etc as though I had fallen down, despite still being suspended.

Expected Results:
No damage until I fell out of the cobweb.

Screenshots:
See below (or possibly above)

Notes:
Takes damage from falling, falling out of the world, lava, those evil prickly bush things (although these don't actually kill you, just hurt a bit), with appropriate death messages.
Does not seem to affect other mobs or entities.
Problem in both Survival and Adventure mode
Damage pattern seems fairly random and interspersed – on the evil prickly bush things this makes sense, but it is odd for falling from a great height
Tested with a 4 * 3 * 2 patch of cobwebs, variously 4 blocks above lava, 3 above evil prickly bush things (I have no idea what they're really called), 16 above the bottom of the world, 15 above a cold, hard, unforgiving stone floor, as well as a similar arrangement 4 blocks above the bottom of the world.