Fix compiler warning / bug from OS X

Change-Id: I498fb6e26642065c32c8425e5e6564bfb7b75c78

python/src/pyarrow/adapters/pandas.cc

@@ -618,7 +618,7 @@ class ArrowDeserializer {
   Status OutputFromData(int type, void* data) {
     // Zero-Copy. We can pass the data pointer directly to NumPy.
     Py_INCREF(py_ref_);
-    OwnedRef py_ref(py_ref);
+    OwnedRef py_ref(py_ref_);
     npy_intp dims[1] = {col_->length()};
     out_ = reinterpret_cast<PyArrayObject*>(PyArray_SimpleNewFromData(1, dims,
                 type, data));