rustfmt ignores #![rustfmt::skip] when run with -r

[topecongiro]

Given the following project structure,

.
├── Cargo.lock
├── Cargo.toml
└── src
    ├── foo.rs
    └── main.rs

// main.rs
mod foo;

fn main() {
    println!("Hello, world!");
}

// foo.rs
#![rustfmt::skip]

fn
foo()
{}

rustfmt src/main.rs -c and rustfmt src/foo.rs -c succeeds but rustfmt -cr src/main.rs will fail with the following output:

Diff in /tmp/skip/src/foo.rs:1:
 #![rustfmt::skip]
 
-fn
-foo()
-{}
+fn foo() {}