Jenkins freezes on sh commands after changing agents

I've added new logic to my Jenkinsfile that in a specific stage I change agents and run commands such as sh.

Problem:

I wanted to change agents and run commands there. However, it seems like a race condition where if the pipeline's agent runs a docker (in the pipeline declarative block), and in one of the stages you change agent, the agent doesn't run shell commands, it just hangs and stays stuck.

Please notice that I want my docker and label to be on the pipeline declaration block and not in specific stages (using agent none), since I want all stages but the last stage to run in this specific agent and specific docker.

Is there a bug in this script? I made a miniature script that reproduces this "bug", you can run this on your own jenkins to try it out for yourself (add docker-credentials to passwords in jenkins), it seems like a bug with jenkins:

#!/usr/bin/env groovy

pipeline
{
    agent
    {
        docker
        {
            alwaysPull true
            image 'ubuntu:xenial'
            registryCredentialsId 'docker-credentials'
            registryUrl 'https://index.docker.io/v1/'
            label 'master'
          }
    }

    stages
    {
        stage("Initialize")
        {
            steps
            {
                script
                {
                    println("Initializing")
                }
            }
        }

        stage("First agent stage")
        {
            steps
            {
                script
                {
                    sh(script: "ls", label: "Working shell scripts")
                }
            }
        }

        stage("Second agent stage")
        {
            agent
            {
                label 'master'
            }
            steps
            {
                script
                {
                    sh(script: "ls", label: "Hung shell scripts")
                }
            }
        }
    }
}

Notice if you change from this:

agent
{
    docker
    {
        alwaysPull true
        image 'ubuntu:xenial'
        registryCredentialsId 'docker-credentials'
        registryUrl 'https://index.docker.io/v1/'
        label 'master'
      }
}

to this:

agent
{
    label 'master'
}

It starts working again...