My take on this (but IANAL) is that you do not really lose the rights to distribute a specific version, but the rights to distribute specific code (or compiled versions of it), and that would carry through to all code in version Y that was already in version X, but not any newer code that is unique to version Y. That won't be very useful, though.
[Edit] Just read the part of the article that deals with this question. Personally, I hold to my take on this matter -- that the scope is not a particular version of the distribution containing the code, but to all the bits of code of which the license was violated -- even if you also have access to the code in another way. My reasoning for this is that this could otherwise open up a pretty simple loop-hole: you'd only have to get someone else, whose license is not yet revoked, to fork the project, and release a new 'version' of the program, to get your rights to the code back. That can not have been the intention of that clause in the GPL.