Base_getPreferredSectionItemList: fix a bug

When existing categoy is not part of the preferred sections the existing category was added to the cache value. Copy the list before.

product/ERP5/bootstrap/erp5_core/SkinTemplateItem/portal_skins/erp5_core/Base_getPreferredSectionItemList.xml

@@ -83,6 +83,7 @@ getPreferredSectionItemList = CachingMethod(getPreferredSectionItemList,\n
 section_item_list = getPreferredSectionItemList(portal_type, validation_state)\n
 \n
 if base_category:\n
+  section_item_list = section_item_list[::] # make a copy not to modify the cache value\n
   current_category = context.getProperty(base_category)\n
   if current_category and current_category not in zip(*section_item_list)[1]:\n
     section_item_list.append(\n

product/ERP5/bootstrap/erp5_core/bt/revision

-41167
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+41168
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