Fix imports in Cython/Include/numpy.pxd.

Cython/Includes/numpy.pxd

@@ -17,9 +17,10 @@
 DEF _buffer_format_string_len = 255
 
 cimport cpython.buffer as pybuf
-from cpython cimport PyObject, Py_INCREF, Py_XDECREF
-from libc cimport stdlib
-from libc cimport stdio
+from cpython.ref cimport Py_INCREF, Py_XDECREF
+from cpython.object cimport PyObject
+cimport libc.stdlib as stdlib
+cimport libc.stdio as stdio
 
 cdef extern from "Python.h":
     ctypedef int Py_intptr_t

tests/run/type_inference.pyx

@@ -363,9 +363,11 @@ def safe_only():
     assert typeof(d) == "long", typeof(d)
 
     # we special-case inference to type str, see
-    # trac # 
+    # trac #553 
     s = "abc"
     assert typeof(s) == "Python object", typeof(s)
+    cdef str t = "def"
+    assert typeof(t) == "str object", typeof(t)
 
     # potentially overflowing arithmetic
     e = 1