title: What is this 'bad:' label generated by Cython?
body: <p>While cythonizing my Cython source code files, I can see a dozen of warnings about a label named 'bad:' generated by Cython, for example:</p>
  <pre><code>read_input.cpp:30037:3: warning: label ‘bad’ defined but not used [-Wunused-label]
  </code></pre>
  <p>The C++ generated function is like this:</p>
  <pre><code>static PyObject* __pyx_convert__to_py_struct__VehicleCaps(struct VehicleCaps s) {
    PyObject* res;
    PyObject* member;
    res = __Pyx_PyDict_NewPresized(0); if (unlikely(!res)) return NULL;
    return res;
    bad:
    Py_XDECREF(member);
    Py_DECREF(res);
    return NULL;
  }
  </code></pre>
  <p>The 'bad:' label is in there, I don't get it why Cython is generating this unused label and it shows warnings.</p>
  <p>Do I have really fix these warnings? or it's safe to leave them untouched?</p>