Attached patch that I tested - resulting in a failure.
The problem is that the upgraded ruleset doesn't get written to a directory named "experimental", and so the game.ruleset reference to "experimental/README.experimental" breaks. Those rulesets that are present also in master get around similar problems by luck, as then such files (typically the README) is found from the master's own ruleset.
Reply To cazfi
Attached patch that I tested - resulting in a failure. The problem is that the upgraded ruleset doesn't get written to a directory named "experimental", and so the game.ruleset reference to "experimental/README.experimental" breaks. Those rulesets that are present also in master get around similar problems by luck, as then such files (typically the README) is found from the master's own ruleset.
#46242 would fix this part.
I think that when https://www.hostedredmine.com/issues/820965 renames experimental ruleset as goldkeep in master, CI will no longer make ruleup test for S3_1 experimental ruleset towards master, as there's no ruleset by that name in master's ruleset_list.txt. Figure out how to make it to work again.