cid#1256663: only allow comparing iterators from the same ring
cid#1256663: only allow comparing iterators from the same ring

Change-Id: I77eb186f0048a9bc335408bace96111e6cb2ca53

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core