1.8.0, confirmed on Discord with 4 people.
Little bit edge case, but:
Turret Prototypes with 0 tracking speed can still be used in turrets.
They also stack infinitely. Anyone up for a Death Star laser made out of 10cm Infrareds?
Damage Output 3 Rate of Fire 15 seconds Range Modifier 10,000
Max Range 1,920,000 km Turret Size 22002.22 HS (1,100,111 tons) HTK 11216
Power Requirement 768 Recharge Rate 256
Cost 170308.96 Crew 954
Maximum Tracking Speed: 0 km/s
Development Cost 1703080 RP
Materials Required
Duranium 76.80
Neutronium 68388.64
Boronide 76.80
Corundium 256.0
(yes, it fires many, many 3-damage shots)
Related, but possibly balance more than bug: turrets even designed with 0 tracking speed still have 10k tracking speed listed when added to the ship, which (since they can also be armored, combine HTK from their weapons, have reduced crew requirement, and have zero gear mass), means that a 0-tracking turret is significantly better than the equivalent quantity of weapons.
DB attached.