serde_json json! macro content got corrupted after `cargo fmt`

[autozimu]

Simplified example main.rs

#[macro_use]
extern crate serde_json;

fn main() {
    let l = vec![1, 2, 3];
    let ret: Vec<_> = l
        .into_iter()
        .map(|i| {
            json!({
                "value": i,
                "value2": i * 2,
            })
        })
    .collect();
}

After running cargo fmt, it becomes

#[macro_use]
extern crate serde_json;

fn main() {
    let l = vec![1, 2, 3];
    let ret: Vec<_> = l.into_iter().map(|i| json!({ "value": i })).collect();
}

As it shows, the second property inside json! was removed.

Expected

cargo fmt/rustfmt should not remove the second property inside json! macro.

Extra Info

$ rustc --version
rustc 1.24.0-nightly (0a3761e63 2018-01-03)
$ cargo fmt --version
0.3.4-nightly ( )

Let me know if extra info is needed. Thanks.

[nrc]

dup of #2338