"Fire spread radius around player" doesn't work when set to 0

I was playing the new snapshot, and I found that when the gamerule “Fire_spread_radius_around_player” is set to 0, fire still spreads from naturally generated lava. Birch trees were caught on fire when I wasn’t paying attention. You’re gonna have to trust me on this. I tried using Lava buckets to mimic the effect, but they don’t do anything. Naturally generated lava does set birch leaves on fire. I don’t know if this affects other blocks, but I am 95% sure that it does affect birch leaves.