Book - Chapter 4.2 - Borrowing multiple mutable reference in same scope

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URL to the section(s) of the book with this problem:
https://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html

Description of the problem:
Able to borrow multiple mutable reference in same scope. It is mentioned in the book that borrowing mutable reference more than once (in same scope) is restricted. But, in the below code, I could borrow mutable reference of s more than once. It compiles and works fine.

fn main() {
let mut s = String::from("hello");
let r1 = &mut s;
r1.push_str("Mutation 1");
let r2 = &mut s;
r2.push_str("Mutation 2");
println!("{s}");

}

Suggested fix:
Issue can be in the book or in compiler. I'm not sure.

Start with the linked Chapter 4.2 section and compare its statement about multiple mutable references with the Rust example in this issue. Check whether the wording or example needs clarification, and consider the issue complete when the book accurately explains why the sequential borrows compile or identifies a concrete correction.