override/*.spec not working
There's no working way to add information about custom flags via override/*.spec.
The inifile format does support multiple section with the same name, so it's not a problem to have the new section in the override .spec, but there's no way to extend existing list (in this case: "sprites"). Assigning a new list causes the existing entries of the list to get replaced. So when one adds one custom nation flag, abkhazia flag information disappears.
I am proposing attached adjustment before formal S3_1-d3f.