i suppose there is a different between order that is not preserved (and thus changes frim run to run) to order that is not defined but predictably consistent.
the questions are: what result would we like to have ideally? do we get that result? if yes, then the result is not going to change and may be documented as such. if no, what is the best description for the current result that will not confuse people even if it changes later?
currently the most correct description seems to be: the order is undefined but consistently the same (for 7.6)
greetings, martin.