added:
```javascript
    test('no duplicate unlock', function() {
      var here = 0;
      Utils.safeCpuLock(15000, function(unlock) {
        setTimeout(function() {
          here++;
          unlock();
        }, 16000);
        here++;
      });
      this.sinon.clock.tick(17000);
      var locks = this.mocklock.getissued();
      assert.equal(locks.length, 1);
      assert.equal(locks[0].unlocks, 1);
      assert.equal(here, 2);
    });
```