python api, slicing works differently on the 64bit ubuntu gutsy system, compared to the 32bit

install.
face.uv[:] was returning a blank list. and making smart UV projection script fail.

On one system Python is giving the slice function positive values, whereas on the 64bit system its 
passing negative which are then clamped to zero.
made mathutils types accept negative values for slicing. This is very odd because both systems are 
running ubuntu gutsy with python 2.5

source/blender/python/api2_2x/vector.c

@@ -359,6 +359,7 @@ static PyObject *Vector_slice(VectorObject * self, int begin, int end)
 	int count;
 
 	CLAMP(begin, 0, self->size);
+	if (end<0) end= self->size+end+1;
 	CLAMP(end, 0, self->size);
 	begin = MIN2(begin,end);
 
@@ -380,6 +381,7 @@ static int Vector_ass_slice(VectorObject * self, int begin, int end,
 	PyObject *v;
 
 	CLAMP(begin, 0, self->size);
+	if (end<0) end= self->size+end+1;
 	CLAMP(end, 0, self->size);
 	begin = MIN2(begin,end);