tests: simplify and deprecate assertSameSet

Since a long time python unittest provides good assertions and we don't need to
build out own.

product/ERP5Type/tests/ERP5TypeTestCase.py

@@ -658,13 +658,8 @@ class ERP5TypeTestCaseMixin(ProcessingNodeTestCase, PortalTestCase):
           genbt5list=1)
 
     def assertSameSet(self, a, b, msg=None):
-      if not msg:
-        try:
-          from pprint import pformat
-        except ImportError:
-          msg='%r != %r' % (sorted(a), sorted(b))
-        else:
-          msg='\n%s\n!=\n%s' % (pformat(sorted(a)), pformat(sorted(b)))
+      """deprecated, please use assertEqual(set(a), set(b))
+      """
       self.assertEqual(set(a), set(b), msg)
     failIfDifferentSet = assertSameSet