Binding a keyboard key to the Gamepad Y button no longer works as expected

How to reproduce: Bind any keyboard button to the "Y" button under the tab "Gamepad" in the menu Keybind. Attempt to press the bound key while casting a spell.
Effect: Jump instead of canceling the cast.
Expected behaviour: Cancel a cast if casting a spell. Jump/move upwards if not casting.

This worked as described in "expected behaviour" before, and didn't interfere for example with spacebar's function in text input like chatting when the spacebar was bound to Y. Pressing the an actual gamepad's Y button works as expected.

You can still cancel casts without moving by pressing close all menus binding (default being Escape, but having jump/cancel casting under the same key is much more preferable). There are situations where you do not want to move an inch while casting spells.

Here are two images to make it clearer what I'm on about, as I expect this to be very niche way of doing things (I only discovered it by accident).

Keybindings:
http://i.imgur.com/T0Aipro.jpg
Gamepad button configuration:
http://i.imgur.com/dfNragf.jpg