Endermen not provoked if looked at below waist.

IIRC this is works as intended

also, the summary contradicts the description.

Please change the summary line to reflect what is happening.
Please also crash the game by pressing F3+C for 10 seconds, and upload the log.

http://www.minecraftwiki.net/wiki/Enderman:

Endermen will become hostile when a player looks at their upper legs, torso, or head.

I think it is a "works as intended". Endearment are not provoked below their waist.

I know, that's what I thought at first, but look closely at the screenshots.

The Endermen is angry when the crosshair is on its legs.
The Endermen is not angry when the crosshair is on its head.