How can I change the branch name using jenkins-cli ?

[user-dev]

I am trying to change the branch of git scm inside jenkins jobs using groovy scipt. But is always getting set to master no matter what values I pass.

for (project in all_jobs){

  

  scm = project.scm;

  //def oldScm = item.getScm()

    println("${project.name}: " +

            "repositories: ${scm.repositories.collectMany{ it.getURIs() }}")

 

  scm.branches = "some-branch"

  println "Test" + scm.branches

}

It prints the changed value but not getting saved