Fix id tool tests.

Some tests were added to check warnings, which were not working in
Python 2 because the warning message was shown just once.
This is fixed by adding a `warnings.simplefilter("always")` inside
the `catch_warnings` context manager, as recommended in
https://docs.python.org/3/library/warnings.html#testing-warnings .
Note that the previous filter is restored on leaving the context
manager.

bt5/erp5_core_test/TestTemplateItem/portal_components/test.erp5.testIdTool.py

@@ -151,6 +151,7 @@ class TestIdTool(ERP5TypeTestCase):
 
     # generateNewId expect str, but convert id_group when passed a wrong type
     with warnings.catch_warnings(record=True) as recorded:
+      warnings.simplefilter("always")
       self.assertEqual(
         self.id_tool.generateNewId(
           id_generator=id_generator,
@@ -168,6 +169,7 @@ class TestIdTool(ERP5TypeTestCase):
         id_group='bytes',
       ), 0)
     with warnings.catch_warnings(record=True) as recorded:
+      warnings.simplefilter("always")
       self.assertEqual(
         self.id_tool.generateNewId(
           id_generator=id_generator,
@@ -269,6 +271,7 @@ class TestIdTool(ERP5TypeTestCase):
 
     # generateNewIdList expect str, but convert id_group when passed a wrong type
     with warnings.catch_warnings(record=True) as recorded:
+      warnings.simplefilter("always")
       self.assertEqual(
         self.id_tool.generateNewIdList(
           id_generator=id_generator,
@@ -287,6 +290,7 @@ class TestIdTool(ERP5TypeTestCase):
         id_count=1,
         ), [0])
     with warnings.catch_warnings(record=True) as recorded:
+      warnings.simplefilter("always")
       self.assertEqual(
         self.id_tool.generateNewIdList(
           id_generator=id_generator,