work around Py3k importlib changes: old-style rel+abs imports are no longer supported

--HG--
extra : transplant_source : K%11N4%9E%E83%3A%3F%84%DFr%7Ca%DEP%22%5D%1B%9E

Cython/Compiler/ExprNodes.py

@@ -9448,6 +9448,24 @@ static PyObject *__Pyx_Import(PyObject *name, PyObject *from_list, long level) {
         goto bad;
     #if PY_VERSION_HEX >= 0x02050000
     {
+        #if PY_VERSION_HEX >= 0x03030000
+        if (level == -1) {
+            /* try relative import first */
+            PyObject *py_level = PyInt_FromLong(1);
+            if (!py_level)
+                goto bad;
+            module = PyObject_CallFunctionObjArgs(py_import,
+                name, global_dict, empty_dict, list, py_level, NULL);
+            Py_DECREF(py_level);
+            if (!module) {
+                if (!PyErr_ExceptionMatches(PyExc_ImportError))
+                    goto bad;
+                PyErr_Clear();
+                level = 0; /* try absolute import on failure */
+            }
+        }
+        #endif
+        if (!module) {
             PyObject *py_level = PyInt_FromLong(level);
             if (!py_level)
                 goto bad;
@@ -9455,6 +9473,7 @@ static PyObject *__Pyx_Import(PyObject *name, PyObject *from_list, long level) {
                 name, global_dict, empty_dict, list, py_level, NULL);
             Py_DECREF(py_level);
         }
+    }
     #else
     if (level>0) {
         PyErr_SetString(PyExc_RuntimeError, "Relative import is not supported for Python <=2.4.");