Unhelpful fatal error with loop in pure mode

(function () {
    function f(a) {
        while (a > 10) {
            a--;
        }
    }
    __optimize(f);
    global.f = f;
})();

In input file /tmp/test.js(3:20) FatalError PP0001:  (https://github.com/facebook/prepack/wiki/PP0001)
    at f (/tmp/test.js:3:20)
Prepack failed, reporting 1 fatal error.
(function () {
  var _$2 = this;

  var _1 = function (a) {
    var __leaked_0;

    var _4 = function () {
      for (; __leaked_0 > 10;) {
        __leaked_0--;
      }
    };

    __leaked_0 = a;

    var _$1 = _4();

    return void 0;
  };

  _$2.f = _1;
}).call(this);