swig4.patch

diff --unified --recursive --text casadi-3.5.1.new/swig/casadi.i casadi-3.5.1/swig/casadi.i
--- casadi-3.5.1.new/swig/casadi.i  2019-11-26 14:04:01.987610235 +0100
+++ casadi-3.5.1/swig/casadi.i  2019-11-26 14:03:37.357450357 +0100
@@ -228,7 +228,7 @@

 import contextlib

-class _copyableObject(_object):
+class _copyableObject(object):
   def __copy__(self):
     return self.__class__(self)