Behavior nestings are kept when an @ensures fails.

Let:

    @behavior alpha { @behavior beta { @behavior gamma { @ensures … } } }

Before:

    The Runtime Assertion Checker has detected failures for…
      • Variable \result does not verify the constraint @ensures…

After:

    The Runtime Assertion Checker has detected failures for…
      • Behavior alpha is broken.
          • Behavior beta is broken.
              • Behavior gamma is broken.
                  • Variable \result does not verify…

Better when tracing or reporting failures.