testERP5WebWithDms: revert the change in Caching Policy Manager not to affect following tests.

bt5/erp5_dms/TestTemplateItem/portal_components/test.erp5.testERP5WebWithDms.py

@@ -656,6 +656,8 @@ class TestERP5WebWithDms(ERP5TypeTestCase, ZopeTestCase.Functional):
     # Those images can be accessible through extensible content
     # url : path-of-document + '/' + 'img' + page-index + '.png'
     # Update policy to have stale values
+    policy_orig = self.portal.caching_policy_manager._policies['unauthenticated no language']
+    try:
       self.portal.caching_policy_manager._updatePolicy(
         "unauthenticated no language", "python: member is None",
         "python: getattr(object, 'getModificationDate', object.modified)()",
@@ -680,7 +682,8 @@ class TestERP5WebWithDms(ERP5TypeTestCase, ZopeTestCase.Functional):
                             (policy.getMaxAgeSecs(),
                              policy.getStaleWhileRevalidateSecs(),
                              policy.getStaleIfErrorSecs()))
-
+    finally:
+      self.portal.caching_policy_manager._policies['unauthenticated no language'] = policy_orig
 
   def test_PreviewOOoDocumentWithEmbeddedImage(self):
     """Tests html preview of an OOo document with images as extensible content.