"""The fact that Python's rule used to be 8 spaces, then got changed to 4 thereby invalidating old code really showed me how shortsighted it is to use a set number of spaces in a whitespace sensitive language."""

When exactly did it use 8 spaces? I have been using Python since 1996 and I don't recall this 8-spaces thing. Almost all code I've seen uses 4 spaces.

In any case, it doesn't matter because, as another commenter pointed out, as long as your indentation is consistent, your code will work just fine, no matter how many spaces you use for indentation. Even if some code does use 8 spaces, it should work without problems. (Tabs as well, by the way... it's mixing tabs and spaces that is a problem.)