Ticket #LHY-526-89006.
Normally, 1.0 mp = 15.0 bc of rush cost (for social and military queues). This is the conversion rate, which is independent of any bonus you get. Or -- is it?
Terran, Large, 5 Godlike. Both planets are from the same game.
1. Peti I gives 18.75 bc/mp.
Turn 89. 207 bc normally takes 13.9 mp (= 208.5 bc). But for this one planet, 11.1 mp suffices for "(1)" turn.
(Clicking Turn does indeed complete it, so it's not lying.)

11.0 is insufficient:

Plug those numbers in:
- 11.0 * 18.75 = 206.250 bc < 207.
- 11.1 * 18.75 = 208.125 bc > 207, regardless of any fraction.
Turn 92. My free colony ship from Benevolent Pioneer has meandered ~70 hexes from Earth, through Krynn home system, north beyond my sensor wagon range, and finally stumbled onto a class 7. (Earth is in the lower left, directly above the "R" in "Riukus".)
In the turn of colonization, obviously zero progress has been made on its 1st build.
An Entertainment Center (30 mp = 450 bc) says outright that it takes "+30 mp".
12.0/30 mp normally takes 2.5 turns, which rounds up to "(3)".
But Riukus II's 12.0 mp suffices for "(2)" turns.