Inserting a conditional `break` in working code causes strange borrowck error

[SNCPlay42]

This code compiles successfully:

pub struct Node {
    left: Option<Box<Node>>,
}

pub fn remove_min(
    root: &mut Option<Box<Node>>,
) {
    let mut p = root;
    while p.as_ref().unwrap().left.is_some() {
        let q = p.as_mut().unwrap();
        p = &mut q.left;
    }
    p.take();
}

I tried this version:

pub struct Node {
    left: Option<Box<Node>>,
}

pub fn remove_min(
    root: &mut Option<Box<Node>>,
) {
    let mut p = root;
    while p.as_ref().unwrap().left.is_some() {
        let q = p.as_mut().unwrap();
        if true { // or any arbitrary expression
            break;
        }
        p = &mut q.left;
    }
    p.take();
}

I expected this to compile successfully.

Instead, this happened:

error[E0499]: cannot borrow `*p` as mutable more than once at a time
  --> <source>:16:5
   |
10 |         let q = p.as_mut().unwrap();
   |                 - first mutable borrow occurs here
...
16 |     p.take();
   |     ^
   |     |
   |     second mutable borrow occurs here
   |     first borrow later used here

error: aborting due to previous error

Meta

Occurs on stable (1.56) on the playground.

Notably, this compiles succesfully with polonius.