check whether avoiding exception in RealUpgradeLayer setup avoids pol…

…luting test environment

plone/app/upgrade/v50/testing.py

@@ -3,8 +3,11 @@
 from plone.testing.z2 import FunctionalTesting, login
 from zope.component.hooks import setSite
 from zope.configuration import xmlconfig
+import logging
 import os
 
+logger = logging.getLogger(__file__)
+
 
 class RealUpgradeLayer(PloneSandboxLayer):
     defaultBases = (PLONE_FIXTURE,)
@@ -25,15 +28,18 @@ def setUpPloneSite(self, portal):
         login(app['acl_users'], 'admin')
 
         # import old ZEXP
-        path = os.path.join(os.path.abspath(
-            os.path.dirname(__file__)), 'data', 'test-full.zexp')
-        app._importObjectFromFile(path, verify=0)
-
-        # run upgrades
-        self['portal'] = portal = app.test
-        setSite(portal)
-        portal.portal_migration.upgrade(swallow_errors=False)
-        setSite(None)
+        try:
+            path = os.path.join(os.path.abspath(
+                os.path.dirname(__file__)), 'data', 'test-full.zexp')
+            app._importObjectFromFile(path, verify=0)
+        except:
+            logger.exception('Failed to import ZEXP from old site.')
+        else:
+            # run upgrades
+            self['portal'] = portal = app.test
+            setSite(portal)
+            portal.portal_migration.upgrade(swallow_errors=False)
+            setSite(None)
 
     def tearDownPloneSite(self, portal):
         del self['portal']