Add last version of review1961002 which works for me

issue1961002_40001.diff

@@ -1,11 +1,12 @@
 Index: trytond/trytond/tests/test_transaction.py
 ===================================================================
+
 --- a/trytond/trytond/tests/test_transaction.py
 +++ b/trytond/trytond/tests/test_transaction.py
 @@ -56,6 +56,41 @@
              Exception, manipulate_cursor, DB_NAME, USER, context=CONTEXT)
          self.assertTrue(empty_transaction(DB_NAME, USER, context=CONTEXT))
- 
+
 +    def test0030set_user(self):
 +        '''
 +        Test set_user
@@ -41,21 +42,25 @@ Index: trytond/trytond/tests/test_transaction.py
 +            with Transaction().set_user(2):
 +                self.assertEqual(transaction.user, 2)
 +
- 
+
  def suite():
      return unittest.TestLoader().loadTestsFromTestCase(TransactionTestCase)
+
 Index: trytond/trytond/transaction.py
 ===================================================================
+
 --- a/trytond/trytond/transaction.py
 +++ b/trytond/trytond/transaction.py
-@@ -118,10 +118,15 @@
+@@ -118,10 +118,16 @@
          return manager
- 
+
      def set_user(self, user, set_context=False):
 +        if user != 0 and set_context:
 +            raise ValueError('set_context only allowed for root')
          manager = _AttributeManager(user=self.user,
-                 context=self.context.copy())
+-                context=self.context.copy())
++                context=self.context)
++        self.context = self.context.copy()
          if set_context:
 -            self.context.update({'user': self.user})
 +            if user != self.user:
@@ -64,4 +69,5 @@ Index: trytond/trytond/transaction.py
 +            self.context.pop('user', None)
          self.user = user
          return manager
- 
+
+

series

@@ -1,2 +1,3 @@
+issue1961002_40001.diff
 issue10739.diff
 issue10467.diff