Rustdoc: strange collapse behaviour when impl block has comment

[tspiteri]

pub struct S;
impl S {
    pub const C1: () = ();
    pub fn foo1() {}
}
/// Comment
impl S {
    pub const C2: () = ();
    pub fn foo2() {}
}
/// Comment
impl S {
    pub const C3: () = ();
    pub fn foo3() {}
}

On the left of the image is the documentation for the three blocks.

1. No comment for the impl block.
2. The comment for the impl block is expanded.
3. The comment for the impl block is collapsed.

On the right, there is what happens when the three impl blocks are collapsed.

1. Collapsed as expected, with both constant and function hidden as expected.
2. The comment is still visible though its [-] is hidden. The function is hidden as expected but the constant is not hidden.
3. The comment is hidden as expected. The function is hidden as expected but the constant is not hidden.