bpo-36430: Fix a possible reference leak in itertools.count(). (GH-12551) (GH-12554)

(cherry picked from commit 0523c39) Co-authored-by: Zackery Spytz <zspytz@gmail.com>

Author: 2 people

Misc/NEWS.d/next/Core and Builtins/2019-03-25-23-37-26.bpo-36430.sd9xxQ.rst

@@ -0,0 +1 @@
+Fix a possible reference leak in :func:`itertools.count`.

Modules/itertoolsmodule.c

@@ -3321,6 +3321,7 @@ count_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
  lz = (countobject *)type->tp_alloc(type, 0);
  if (lz == NULL) {
  Py_XDECREF(long_cnt);
+ Py_DECREF(long_step);
  return NULL;
  }
  lz->cnt = cnt;