Lockable resources plugin doesn't assign resource if an env variable is used as label

pipeline {
  agent {
    node { label 'centos_node' }
  }

  stages {
    stage("Setup") {
      steps {
        script {
          env.NODE_LABEL = "pre_commit"
        }
      }
    }
    stage ("Build") {
      options {
        lock(label: "${env.NODE_LABEL}", variable: "NODELABEL", quantity: 1)
      }
      steps {
        script {
          sh "echo \"${env.NODELABEL}\""
        }
      }
    }
  }
}

 +refs/heads/master:refs/remotes/origin/master # timeout=10
 Checking out Revision 9db4337fd2811d9ebce79f1761ef40a88ec16fb2 (master)
 > git config core.sparsecheckout # timeout=10
 > git checkout -f 9db4337fd2811d9ebce79f1761ef40a88ec16fb2 # timeout=10
 Commit message: "send slack for only master builds"
 > git rev-list --no-walk 9db4337fd2811d9ebce79f1761ef40a88ec16fb2 # timeout=10[Pipeline] nodeRunning on codereview1.eng.nutanix.com in /root/workspace/QA/test_lock[Pipeline] {[Pipeline] stage[Pipeline] { (Setup)[Pipeline] script[Pipeline]

{[Pipeline] }

[Pipeline] // script[Pipeline] }[Pipeline] // stage[Pipeline] stage[Pipeline] { (Build)[Pipeline] lockTrying to acquire lock on [Label: null, Quantity: 1]
 Found 0 available resource(s). Waiting for correct amount: 1.
 *[Label: null, Quantity: 1] is locked, waiting...*