I actually went ahead and asked Linus Torvalds himself. He said he'd never use spaces, and always used tabs from the get go. So, my theory fails :)

> What? No.

> It always used tabs.

> And by "always used tabs" I mean "mistakes probably happened, and there may be spaces in some places", but afaik I've always used hard-tabs as the normal indentation.

> If you see something else, you probably have some archive that has been reformatted.