No formatting for match arms containing /*...*/ comments

rustfmt 0.5.0

this code:

``` rust
fn test(value: u8) {
    match value {
    0 => {
            fn1();
        }
            _ /*comment*/ => {
            fn2();
        }
    }
}
```

should be formatted as follows:

``` rust
fn test(value: u8) {
    match value {
        0 => {
            fn1();
        }
        _ /*comment*/ => {
            fn2();
        }
    }
}
```

but it's not.
