Menu links never actually link to the full path of a MENU_DEFAULT_LOCAL_TASK, only its parent.
/admin/structure/views <-- Parent
/admin/structure/views/basic <-- Default local task
/admin/structure/views/advanced <-- Local task
As a part of, we're considering making the actual default local task path 404.
I'm not 100% sure if
I believe that the db_select() in menu_contextual_links() is actually the issue.