use another session to get password update

backend/tracim_backend/lib/core/user.py

         )
         if do_save:
             # TODO - G.M - 2018-07-24 - Check why commit is needed here
-            transaction.commit()
+            self.save(user)
         return user
 
     def set_email(

backend/tracim_backend/tests/functional/test_user.py

             status=204,
         )
         # Check After
+        dbsession = get_tm_session(self.session_factory, transaction.manager)
+        uapi = UserApi(
+            current_user=admin,
+            session=dbsession,
+            config=self.app_config,
+        )
         user = uapi.get_one(user_id)
         assert not user.validate_password('pass')
         assert user.validate_password('mynewpassword')
             params=params,
             status=403,
         )
+        dbsession = get_tm_session(self.session_factory, transaction.manager)
+        uapi = UserApi(
+            current_user=admin,
+            session=dbsession,
+            config=self.app_config,
+        )
         # Check After
         user = uapi.get_one(user_id)
         assert user.validate_password('pass')
             status=400,
         )
         # Check After
+        dbsession = get_tm_session(self.session_factory, transaction.manager)
+        uapi = UserApi(
+            current_user=admin,
+            session=dbsession,
+            config=self.app_config,
+        )
         user = uapi.get_one(user_id)
         assert user.validate_password('pass')
         assert not user.validate_password('mynewpassword')
             status=204,
         )
         # Check After
+        dbsession = get_tm_session(self.session_factory, transaction.manager)
+        uapi = UserApi(
+            current_user=admin,
+            session=dbsession,
+            config=self.app_config,
+        )
         user = uapi.get_one(user_id)
         assert not user.validate_password('pass')
         assert user.validate_password('mynewpassword')