After upgrading to 1.597 from 1.588 on Windows

• I cannot downgrade because trying to run the unmigrate script fails with:

  Exception in thread "main" java.lang.NoClassDefFoundError: javax/servlet/http/HttpServletRequest
          at hudson.Util.createSymlinkJava7(Util.java:1224)
          at hudson.Util.createSymlink(Util.java:1118)
          at jenkins.model.RunIdMigrator.unmigrateBuildsDir(RunIdMigrator.java:371
  )
          at jenkins.model.RunIdMigrator.unmigrateJobsDir(RunIdMigrator.java:320)
          at jenkins.model.RunIdMigrator.main(RunIdMigrator.java:307)
  Caused by: java.lang.ClassNotFoundException: javax.servlet.http.HttpServletRequest
          at java.net.URLClassLoader$1.run(Unknown Source)
          at java.net.URLClassLoader$1.run(Unknown Source)
          at java.security.AccessController.doPrivileged(Native Method)
          at java.net.URLClassLoader.findClass(Unknown Source)
          at java.lang.ClassLoader.loadClass(Unknown Source)
          at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
          at java.lang.ClassLoader.loadClass(Unknown Source)
          ... 5 more