Avoid to store in transactional cache former translation value

Translated fields are stored in the transactional cache. Using the instance to
get the source value when it is being set, store the former value into the
cache and the source.

issue7997
review58471002

trytond/ir/translation.py

@@ -471,12 +471,16 @@ class Translation(ModelSQL, ModelView):
                 to_save = []
                 for record, value in zip(records, values):
                     translation = translations.get(get_name(record))
+                    if lang == 'en':
+                        src = value
+                    else:
+                        src = getattr(record, field_name)
                     if not translation:
                         translation = cls()
                         translation.name = name
                         translation.lang = lang
                         translation.type = ttype
-                    translation.src = getattr(record, field_name)
+                    translation.src = src
                     translation.value = value
                     translation.fuzzy = False
                     to_save.append(translation)
@@ -512,6 +516,10 @@ class Translation(ModelSQL, ModelView):
             to_save = []
             for record, value in zip(records, values):
                 translation = translations.get(record.id)
+                if lang == Config.get_language():
+                    src = value
+                else:
+                    src = getattr(record, field_name)
                 if not translation:
                     translation = cls()
                     translation.name = name
@@ -519,19 +527,14 @@ class Translation(ModelSQL, ModelView):
                     translation.type = ttype
                     translation.res_id = record.id
                 else:
-                    cls.write([translation], {
-                        'value': value,
-                        'src': getattr(record, field_name),
-                        'fuzzy': False,
-                        })
                     other_langs = other_translations.get(record.id)
                     if other_langs:
                         for other_lang in other_langs:
-                            other_lang.src = getattr(record, field_name)
+                            other_lang.src = src
                             other_lang.fuzzy = True
                             to_save.append(other_lang)
                 translation.value = value
-                translation.src = getattr(record, field_name)
+                translation.src = src
                 translation.fuzzy = False
                 to_save.append(translation)
             cls.save(to_save)

trytond/tests/test_field_char.py

@@ -453,6 +453,24 @@ class FieldCharTranslatedTestCase(unittest.TestCase, CommonTestCaseMixin):
     def Char(self):
         return Pool().get('test.char_translate')
 
+    @with_transaction()
+    def test_translation_default_language_cache(self):
+        """Test set translation for default language does not fill transactional
+        cache with former value"""
+        pool = Pool()
+        Config = pool.get('ir.configuration')
+        Char = self.Char()
+
+        with Transaction().set_context(language=Config.get_language()):
+            char, = Char.create([{
+                        'char': "foo",
+                        }])
+
+            char.char = "bar"
+            char.save()
+
+            self.assertEqual(char.char, "bar")
+
 
 class UnaccentedTestCase(unittest.TestCase):
     @classmethod