CatalogTool: fix upgradeSchema with python scripts

Python scripts can be used as catalog methods, including as "clear catalog"
methods. This was causing error when upgradeSchema was called:

    product/ERP5Catalog/CatalogTool.py", line 1372, in upgradeSchema
      method_list_by_connection_id[method.connection_id].append(method)
    AttributeError: connection_id

product/ERP5Catalog/CatalogTool.py

@@ -1369,7 +1369,8 @@ class CatalogTool (UniqueObject, ZCatalog, CMFCoreCatalogTool, ActiveObject):
       method_list_by_connection_id = defaultdict(list)
       for method_id in catalog.sql_clear_catalog:
         method = catalog[method_id]
-        method_list_by_connection_id[method.connection_id].append(method)
+        if hasattr(aq_base(method), 'connection_id'):
+          method_list_by_connection_id[method.connection_id].append(method)
 
       # Because we cannot select on deferred connections, _upgradeSchema
       # cannot be used on SQL methods using a deferred connection.

product/ERP5Catalog/tests/testERP5Catalog.py

@@ -4137,3 +4137,13 @@ class CatalogToolUpgradeSchemaTestCase(ERP5TypeTestCase):
     with self.assertRaisesRegexp(ProgrammingError,
                                  r"Table '.*\.table1' doesn't exist"):
       self.query_connection_2("SELECT b from table1")
+
+  def test_upgradeSchema_python_script(self):
+    method = self.catalog.newContent(
+        portal_type="Python Script",
+        id=self.id(),
+        body="print('for example, create initial data')")
+    self.catalog.setSqlClearCatalogList([method.getId()])
+    self.commit()
+
+    self.catalog_tool.upgradeSchema(sql_catalog_id=self.catalog.getId())