memory leak - C API

[John Hunter]

I have a function that is leaking memory; I have removed all the
extraneous code just to focus on the leak.  This function contains the
leak

static PyObject *
pokereval_debug_leak(PyObject *self, PyObject *args)
{
  
  int i, N;
  char* cardstr;
  PyObject* player0;
  PyObject* player1;
  if (!PyArg_ParseTuple(args, "OO", &player0, &player1)) {
    PyErr_SetString(PyExc_ValueError, 
		    "Usage compare_two_hands(player0, player1)");

    return NULL;
  }


  
  N = PySequence_Length(player0);
  
  // init the pokereval vars from the python args
  for (i=0; i<N; ++i) {
    cardstr = PyString_AsString(PySequence_GetItem(player0, i));   //no leak
    cardstr = PyString_AsString(PySequence_GetItem(player1, i)); //leak
  }
  
  return Py_BuildValue("(iiif)", 0,0,0,0.0);

}


The python code that calls this function is

    for s in enumerate_down(down, common):
        player1 = s.split()
        wins, losses, ties, ev = debug_leak( player0, player1 )

Ie, player0 is the same in every call and player 1 is created on each
iteration through the loop.  player0 and player1 are equal length
tuples of strings.

Am I doing something wrong vis-a-vis memory handling?  Only the
player1 line in the C code labeled "leak" produces a detectable leak
(determined by selective commenting out).  My understanding is that
PySequence_GetItem returns a borrowed ref so I don't need to do any
memory management.  What about PyString_AsString.  It's interesting to
me that the leak is dependent on how the object was created in the
python code.

If I change the loop to 

    opponentDown = ('AH', 'QD')
    for s in enumerate_down(down, common):
        wins, losses, ties, ev = debug_leak( tuple(down), tuple(opponentDown) )

I have no detectable leak.  If the code is erroneous (most likely!),
please let me know where.  If not, I'll write up a complete, free
standing example that replicates it.

Thanks