[FIX] P3: assertItemsEqual is called assertCountEqual

The python 3 name is more correct as to what the assertion actually
does, but still makes for a breaking change.

odoo/tests/common.py

@@ -23,6 +23,8 @@ from pprint import pformat
 
 import requests
 
+from odoo.tools import pycompat
+
 try:
     from itertools import zip_longest as izip_longest
 except ImportError:
@@ -158,6 +160,10 @@ class BaseCase(TreeCase):
         doc = self._testMethodDoc
         return doc and ' '.join(l.strip() for l in doc.splitlines() if not l.isspace()) or None
 
+    if not pycompat.PY2:
+        # turns out this thing may not be quite as useful as we thought...
+        def assertItemsEqual(self, a, b, msg=None):
+            self.assertCountEqual(a, b, msg=None)
 
 class TransactionCase(BaseCase):
     """ TestCase in which each test method is run in its own transaction,