incomplete error test case for cdef class attribute assignments

tests/errors/extclassattrsetting.pyx

+__doc__ = u"""
+>>> e = ExtClass()
+>>> e.get()
+5
+"""
+
+cdef class ExtClass:
+    cdef int _attribute = 2
+
+    def get(self):
+        return self._attribute
+
+    _attribute = 5     # FIXME: this is not currently handled!!!
+
+_ERRORS = u"""
+8:13: Cannot assign default value to cdef class attributes
+"""