error[E0119]: conflicting implementations of trait `Clone` for type `&mut MyType`
  --> $DIR/coherence-conflicting-repeated-negative-trait-impl-70849.rs:8:1
   |
LL | impl !Clone for &mut MyType {}
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: conflicting implementation in crate `core`:
           - impl<T> !Clone for &mut T
             where T: ?Sized;

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0119`.