Getting the indentation right should be the least of your worries if you have a good editor (and don't do something like mix spaces and tabs, which I think everyone is in general agreement with across all languages).

When was the last time that you manually typed out 4 (or 2, or 8, etc) spaces to indent a line of code vs. just hitting tab and letting the editor handle inserting those spaces (or the editor automatically indenting when you hit enter on the previous line)?

As an aside, all of the people that I've met in person that get red in the face over the idea of white space being semantic are the sort of people that write code like this:

  sub function1 { return map { $_[2]->do_something($_) } @{shift->(@_)[0]} }

I'm sorry, but I can't get worked up about not being able to write code like that.

Note: the above code is a reasonable approximation of actual code I encountered by an actual person that would get visibly upset about Python's semantic white space.

P.S. The two '$_'s in the map block actually refer to two different variables, and this is one of the reasons I remember that bit of code. It makes no sense to mix usage like that because it becomes confusing.