Weird formatting of asm! statement within macro definition

[IsaacWoods]

Niche use-case maybe, but this is what the current nightly rustfmt (rustfmt 0.8.2-nightly (173ae0d 2018-05-28)) produces:

macro_rules! save_regs {
    () => {
        asm!("push rax
              push rcx
              push rdx
              push rsi
              push rdi
              push r8
              push r9
              push r10
              push r11"
                                     :::: "intel", "volatile");
    };
}

Specifically, the indentation before the colons seems excessive?