If bukkit.yml doesn't include that line, then delete it entirely and let it regenerate.
Here is an example bukkit.yml.
settings:
allow-end: true
warn-on-overload: true
spawn-radius: 16
permissions-file: permissions.yml
update-folder: update
ping-packet-limit: 25
use-exact-login-location: false
plugin-profiling: false
ticks-per:
animal-spawns: 400
monster-spawns: 1
auto-updater:
enabled: false
on-broken:
- warn-console
- warn-ops
on-update:
- warn-console
- warn-ops
preferred-channel: rb
host: dl.bukkit.org
suggest-channels: true
database:
username: bukkit
isolation: SERIALIZABLE
driver: org.sqlite.JDBC
password: walrus
url: jdbc:sqlite:{DIR}{NAME}.db
aliases:
icanhasbukkit:
- version