Renamed c, a, d, u to modified, added, removed, unknown for users of changes()
%%% should show a removed and b addedA bR areverting...%%% should show b unknown and a back to normal? bmerging a%%% should show foo-bfoo-b%%% should show a removed and b addedA bR areverting...%%% should show b unknown and a marked modified (merged)? b%%% should show foo-bfoo-b