Hostile mobs spawn from spawners if spawn-monsters is set to false

The spawn-monsters server setting does not prevent mobs to spawn from spawners.

Steps to reproduce

1. Open server.properties
2. Set spawn-monsters=false
3. Start the server and join it
4. Find a monster spawner or trial spawner

Actual Results

No monsters should spawn since monster spawning is disabled for the server

Observed Results

Monsters still spawn from the spawners