This was extremely borked:
The priority overrides for refinery, production and silo ignored power completely and never checked whether the structure might drive the AI into low power state; whereas the check for regular building checked whether the structure's power -exceeded- MinimumExcessPower (previously just 0). The catch is that power draw is represented by negative numbers, so the only buildings that would trigger this were - power plants.
Now it checks whether the sum of building power draw (negative) and AI's current power level are lower than MinimumExcessPower, if not, build the structure, if yes, build a power plant instead.
Additionally, this check is now performed for the early-game priority overrides as well.
Last but not least the AI would not(!) give power plants priority if it was already low on power. This has been fixed as well.
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