On Fri, May 16, 2014 at 3:42 PM, Mateusz Kowalczyk <fuuzetsu@fuuzetsu.co.uk> wrote:

It does not matter I feel because you're encouraged to detab in a
separate patch anyway so blaming will show that whether it's all done at
once or separately.

It's indeed a minor reason. I think the thinking is that if you're changing a file any way you 1) will touch a bunch of the same lines for other reasons than detabbing and 2) you know something about the code so blaming you is less bad. :)