Why the `cycle()` method exists if `ChunksMut` is never `Clone?`

The https://doc.rust-lang.org/std/slice/struct.ChunksMut.html has the cycle method: https://doc.rust-lang.org/std/iter/struct.Cycle.html#method.cycle that works only when Self: Clone

However, ChunksMut does not implement Clone, therefore I cannot do this:

fn main() {
    let a = &[1,2,3,4,5,6];
    let mut chunks = a.chunks_mut(2);
    let cycle = chunks.cycle();
    for c in cycle {
        
    }
}

Why the cycle() method exists if ChunksMut is never Clone?