D2: Indexed format specifiers?

[Nick Sabalausky]

I could have sworn I saw Andrei say somewhere a while ago that Phobos2 
supported posix-style indexed format specifiers. From what I could figure 
out from some searching that on the web, those are like "%1$s". But this 
gives me a FormatException:

"%1$s".format("A");

And this works fine:

"%s".format("A");

Did I get the format wrong?