Trying to run steps on many slaves in parallel, but when the `doStuff(x)` closure is executed the slave name argument being passed (`x`) is always "slave3"

Jenkinsfile

def onEachSlave(doStuff) {
  def doStuffClosures = [:]
  for (slave in ['slavelnx1', 'slavelnx2', 'slavelnx3']) {
    def s = slave
    doStuffClosures[s] = { echo "running on ${s}..."; doStuff(s); echo "...done on ${s}!" }
  }
  return doStuffClosures
}
parallel(onEachSlave { slave ->
    echo "doing stuff on ${slave}..."
})

Output

[Pipeline] parallel
[Pipeline] [slavelnx1] { (Branch: slavelnx1)
[Pipeline] [slavelnx2] { (Branch: slavelnx2)
[Pipeline] [slavelnx3] { (Branch: slavelnx3)
[Pipeline] [slavelnx1] echo
[slavelnx1] running on slavelnx1...
[Pipeline] [slavelnx2] echo
[slavelnx2] running on slavelnx2...
[Pipeline] [slavelnx3] echo
[slavelnx3] running on slavelnx3...
[Pipeline] [slavelnx1] echo
[slavelnx1] doing stuff on slavelnx3
[Pipeline] [slavelnx1] echo
[slavelnx1] ...done on slavelnx1!
[Pipeline] [slavelnx1] }
[Pipeline] [slavelnx2] echo
[slavelnx2] doing stuff on slavelnx3
[Pipeline] [slavelnx2] echo
[slavelnx2] ...done on slavelnx2!
[Pipeline] [slavelnx2] }
[Pipeline] [slavelnx3] echo
[slavelnx3] doing stuff on slavelnx3
[Pipeline] [slavelnx3] echo
[slavelnx3] ...done on slavelnx3!
[Pipeline] [slavelnx3] }
[Pipeline] // parallel
[Pipeline] End of Pipeline