Summary: Ever since 15w49a when fire extinguishing rates were changed from 0 - 45% to 20 - 65% fire extinguishes very quickly, in the screenshots, the fire is extinguished so fast, that it can't even spread. If the fire ever destroys a block, it is rare. The difficulty was hard in this test.

Reproduction Steps:
1. Create a world.
2. Find a forest or place lots of flammable blocks.
3. Use this command: /toggledownfall
4. Light some of the flammable blocks on fire, make sure they're exposed to the rain. (Preferably light 1 - 5 blocks)
5. Notice the behavior of the flames, rarely does it spread or destroy a block.