Inconsistent Formatting with non-ASCII characters

[JP-Ellis]

It appears that rustfmt does not always format essentially identical lines the same, and in this case the only difference is that one line has only ASCII characters, while the other has non-ASCII characters. The specific example I have (after formatting):

pub fn foo(config: &Config) {
    let csv = RefCell::new(create_csv(config, "foo"));
    {
        let mut csv = csv.borrow_mut();
        for (i1, i2, i3) in iproduct!(0..2, 0..3, 0..3) {
            csv.write_field(format!("γ[{}.{}.{}]", i1, i2, i3))
                .unwrap();
            csv.write_field(format!("d[{}.{}.{}]", i1, i2, i3)).unwrap();
            csv.write_field(format!("i[{}.{}.{}]", i1, i2, i3)).unwrap();
        }
        csv.write_record(None::<&[u8]>).unwrap();
    }

where each line within the iproduct! loop should be identical as they are all exactly the same length; however, the line with the γ letter is formatted differently to the other two.

Note I am using rustfmt 1.0.3-stable (d6829d6 2019-02-14)

[scampi]

Another issue that seems related #3235 it had a PR but looks like it missed some cases!