Cloning full Git repository can take a long time (in my case over 10 minutes which results in timeout).

In the freestyle project I can specify additional clone options like shallow clone. Unfortunatelny I cannot do this in Multibranch Pipeline project with Jenkinsfile.

I've tried modifying scm.extensions using code like this:

@NonCPS
def checkout_src() {
  def copt = new CloneOption(true, "", 999)

  def r = scm.extensions.add(copt)

  echo "${scm.extensions}"

  checkout scm

  scm.extensions.remove(copt)
}

However when executed CloneOption is not added to extensions:

Extensions: [hudson.plugins.git.extensions.impl.BuildChooserSetting@87d105]

It would be nice if it was possible to add extensions to SCM via Jenkinsfile.