Graves sometimes glitch through the floor when dying from fall damage

[zarunet]

When dying from fall damage on a surface that is only 1 block thick, the grave sometimes appears below that surface instead of above, where the death actually occurred.

This does not happen every time, and i suspect that velocity at impact might play a role in this.

As far as i'm aware, there are no other mods installed on my server that mess with inventory or death management.