I had defined a working email extension in one of my templates that fired off emails in certain cases.  This extension defined the following groovy pre-send script:

def getReplacementIndicatorFile(subproject) {
     if (subproject == null) {
          build.getWorkspace().child('build').child('replaceInfo.txt')
     } else {
          build.getWorkspace().child(subproject).child('build').child('replaceInfo.txt')

          }
}
if (this.hasProperty("RAWSUB")) {
    def replaceInfoFile = getReplacementIndicatorFile("${RAWSUB}")  
    logger.println("replaceInfoFile=${replaceInfoFile}")
    if (replaceInfoFile.exists()) {
        msg.text = replaceInfoFile.readToString()
    } else {
        cancel = true

        }
} else {
   cancel = true
}

This script now fails with the following error:

Pre-send script tried to access secured objects: classpath entry file:/ is a class directory, which are not allowed.
ERROR: Could not send email as a part of the post-build publishers.
org.jenkinsci.plugins.scriptsecurity.scripts.UnapprovedClasspathException: classpath entry file:/ is a class directory, which are not allowed.
        at org.jenkinsci.plugins.scriptsecurity.scripts.ScriptApproval.using(ScriptApproval.java:570)
        at hudson.plugins.emailext.ExtendedEmailPublisher.expandClasspath(ExtendedEmailPublisher.java:678)
        at hudson.plugins.emailext.ExtendedEmailPublisher.executeScript(ExtendedEmailPublisher.java:620)
        at hudson.plugins.emailext.ExtendedEmailPublisher.executePresendScript(ExtendedEmailPublisher.java:573)
        at hudson.plugins.emailext.ExtendedEmailPublisher.sendMail(ExtendedEmailPublisher.java:456)
        at hudson.plugins.emailext.ExtendedEmailPublisher._perform(ExtendedEmailPublisher.java:441)
        at hudson.plugins.emailext.ExtendedEmailPublisher.perform(ExtendedEmailPublisher.java:349)
        at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:20)
        at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:744)
        at hudson.model.AbstractBuild$AbstractBuildExecution.performAllBuildSteps(AbstractBuild.java:690)
        at hudson.model.Build$BuildExecution.cleanUp(Build.java:196)
        at hudson.model.Run.execute(Run.java:1771)
        at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
        at hudson.model.ResourceController.execute(ResourceController.java:97)
        at hudson.model.Executor.run(Executor.java:421)
Finished: SUCCESS

Since my script says nothing about the classpath, I wonder what I would need to do to set up a classpath for my script that does not produce this error.  Why is file:/ the default classpath?

Also, nothing is available in the script approval page that I can approve to get around this.

This issue was not present prior to the upgrade to the above versions.