¿Cómo obtengo una referencia mutable de un vector?

Tanto los métodos run como send necesitan un objeto self, y la función send también necesita una referencia mutable de Packet:

struct Package {
    id: u32,
}

impl Package {
    fn new(id: u32) -> Package {
        Package { id }
    }
}

struct Manager {
    packages: Vec<Package>,
}

impl Manager {
    fn new() -> Manager {
        Manager {
            packages: vec![
                Package::new(1),
                Package::new(2),
                Package::new(3),
                Package::new(4),
            ],
        }
    }
    fn run(&mut self) {
        for package in self.packages.iter_mut() {
            if package.id == 1 {
                self.send(package);
            }
            println!("{}", package.id);
        }
    }
    fn send(&self, package: &mut Package) {
        package.id = 23;
    }
}

fn main() {
    let mut manager = Manager::new();
    manager.run();
}

<p>“`none
error[E0502]: cannot borrow *self as immutable because it is also borrowed as mutable
–> src/main.rs:29:17
|
27 | for package in self.packages.iter_mut() {
| ————————
| |
| mutable borrow occurs here
| mutable borrow later used here
28 | if package.id == 1 {
29 | self.send(package);
| ^^^^ immutable borrow occurs here

error[E0596]: cannot borrow manager as mutable, as it is not declared as mutable
–> src/main.rs:41:5
|
40 | let manager = Manager::new();
| ——- help: consider changing this to be mutable: mut manager
41 | manager.run();
| ^^^^^^^ cannot borrow as mutable
“`

¿Cómo puedo refactorizar estas dos funciones para que funcionen?

No quiero copiar el paquete, ya que eso causaría muchos problemas con mi código original.