Why does xf86-input-evdev ignore the xkb_rules option?

[Martin Burggraf]

Hi,
 
I have an input device/keyboard, which I reconfigured greatly, wrote my own geometry files, symbols, keycodes and so on.
To make it work with X11 I wanted to write my own rules file for use with the xf86-input-evdev package. However I had to notice, that it doesn't work, because when using

Driver "evdev"

In the Config file, the statement
Option "XkbRules" "myfile"
is ignored.

In  xf86-input-evdev src/evdev.c I found line 1152 and follwing:
   /* sorry, no rules change allowed for you */
    xf86ReplaceStrOption(pInfo->options, "xkb_rules", "evdev");
    rmlvo.rules = xf86SetStrOption(pInfo->options, "xkb_rules", NULL);

So the code explicitly ignores the option. As a result I have to make my rules changes to the file /usr/share/X11/xkb/rules/evdev itself, which isn't quite update stable and a hassle for me.

Is there an explanation, on why exactly the option to specify a different rule-file is disabled? I guess there must be a good reason, but I can't find any info on it.

Best Regards
Martin