some modules needed for x11-wm/i3 test phases

I'm not entirely sure thats the case, but of course, IANAL. The wording of that phrase in GPL1 implies Its only "GPL1+" if the legal says so. 

> Each version is given a distinguishing version number.  If the Program
specifies a version number of the license which applies to it and "any
later version", you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation.  If the Program does not specify a version number of the license, you may choose any version ever published by the Free Software Foundation

The implication I read here is that the absence of such an "or later" phrase implies "only".

And so, it appears we're communicating this difference via our `LICENSE` field.

After all, that is why we have both `GPL-1` and `GPL-1+` in tree right?