revset: fix iteration over ordered addset composed of non-ordered operands Before this change, doing ordered iteration over an 'addset' object composed of operands without fastasc or fastdesc method could result in duplicated entries. This was the result of applying '_iterordered' on an unordered set. We fix it by ensuring we iterate over the set in a sorted order. Using the fast iterator when it exists on any operand. We kill the '_iterator' method in the process because it did not make a lot of sense independently. Thanks goes to Yuya Nishihara for reporting the issue and analysing the cause.