Description of problem:
Unable to map the Escape key to one of the buttons on a Wacom Cintiq 22HD pad. All other modifier keys work (alt/ctrl etc.).

Version-Release number of selected component (if applicable):
xorg-x11-drv-wacom-0.16.1-3.el6.x86_64 on Red Hat Enterprise Linux 6

How reproducible:
Consistent.


Steps to Reproduce:
1. Try and set escape to one of the buttons on the Wacom tablet:
   $ xsetwacom --set "Wacom Cintiq 22HD pad" Button 13 "key  Esc"
The command doesn't return any error, but the key isn't mapped.

  
Actual results:
Running a get results in a null:
$ xsetwacom --get "Wacom Cintiq 22HD pad" Button 13
key +(null) -(null) 

Expected results:
The button on the pad should be mapped to Escape

Additional info:

Output from xev:

KeyPress event, serial 34, synthetic NO, window 0x8600001,
    root 0x1f5, subw 0x0, time 946082789, (89,118), root:(3636,1033),
    state 0x10, keycode 8 (keysym 0x0, NoSymbol), same_screen YES,
    XLookupString gives 0 bytes: 
    XmbLookupString gives 0 bytes: 
    XFilterEvent returns: False

KeyRelease event, serial 34, synthetic NO, window 0x8600001,
    root 0x1f5, subw 0x0, time 946082789, (89,118), root:(3636,1033),
    state 0x10, keycode 8 (keysym 0x0, NoSymbol), same_screen YES,
    XLookupString gives 0 bytes: 
    XFilterEvent returns: False