The combination of choice/case/augment/choice/case traversal seems to have a logical bug in it. For this model:

module foo {
  namespace foo;
  prefix foo;

  container foo;

  augment /foo {
    choice bar {
      case baz;
    }
  }

  augment /foo/bar/baz {
    choice xyzzy;
  }
}

it seems ChoiceNodeContextNode does the wrong thing in that the traversal from baz to xyzzy does not include the augment holding xyzzy.