The bug

When a moss block is bonemealed, it can turn adjacent blocks into moss, even if they are in spawn srotection.

Steps to reproduce

You'll need a server with spawn protection active to reproduce this bug.

1. Place a moss block just outside spawn protection, at ground level.
2. Maye sure that you're are not an OP, so that Spawn Protection affects you.
3. Bonemeal the moss block

Activating spawn protection

1. Make sure at least one other player is an OP:

   /op Notch
   

2. Make sure that the world has an explicit spawn point:

   /setworldspawn ~ ~ ~
   

3. Operators bypass spawn protection, so deop yourself:

   /deop <username>
   

4. Try to break/place some blocks near the world spawnpoint to test if spawn protection is active

Observed behaviour

The moss spreads into Spawn Protection

Expected behaviour

The moss would not spread into the Spawn Protection area