Fedora to switch to Python 3 by default

Actually most languages got that right by now: Java, C#, Scala, F#, Haskell, Ocaml, SML. Even dynamically-typed ones like Scheme or Ruby. And while not quite strongly-typed, even in C++ the type of 1 == 1 is bool, not int.

In C++ type of 1 == 1 may be bool, not int, but this is still perfectly valid C++:

bool foo(bool a, bool b) {
  return a + b;
}

And this is valid, too:

int bar(float x) {
  if (x)
    return 42;
  else
    return 0;
}

Python doesn't even have a static type system, how is it supposed to guarantee anything?

With it's dynamic type system, obviously. If type of object is bool then it's either True or False. And you can even create a nice syntax with decorators!

Hell, Python doesn't even guarantee that True is true, True = False being a valid statement.

That's another side of the python's coin: many constructions which use reserved words in python don't use them and thus can be broken. len = False and range = False are valid, too, but it does not mean they should not use len or range!

Oh, and by the way: int guarantees that a variable contains either zero or non-zero, which is entirely isomorphic.

Sure. And you can even go further and use double instead of int everywhere (as JavaScript does), but it does not mean it's good idea.

They may be defined, but how are they useful?

They are useful when you need to do certain things. Namely: check is some non-boolean variable contains zero or if you want to transform code bool to some flag (in such a case you need to multiply bool by int, of course) or just calculate some kind of weight (where each bool will have one).

One may argue that it's probably not as important and safety will be preferable, but this is separate issue and in a language where you can store float value in an int variable (or the other way around) these look quite natural. Heck, even enum can participate in arithmetic in C! I would be surprised to see bool which can not be used in such a way in C—especially since C++ also allows that.

Bottom line: everybody agrees that C not having strongly-typed booleans is error-prone and useless.

Where everybody is defined as “anyone who's nick is HelloWorld”? It's error-prone, true, but you are the only one who claims that it's useless.

Every time you include a header you can break code because somebody #defined an identifier you're using.

And you can find it and #undef it.

Every time you use strict; you break legacy code.

There are no use strict; in C.

What you're saying is essentially that Perl should never have bothered with use strict;.

No, what I'm saying it that use strict; (and it's GCC's analogue -Werror) must be implemented as capability which is entirely decoupled from all other features. You want to mix it with something else. Sorry, but this is not useful and just plain wrong.