Removal of the symlinks lastFailedBuild,lastUnstableBuild and lastUnsuccessfulBuild does result in a correct backup.
Error message:
Jul 22, 2013 1:13:27 PM org.jvnet.hudson.plugins.thinbackup.ThinBackupPeriodicWork backupNow
SEVERE: Cannot perform a backup. Please be sure jenkins/hudson has write privileges in the configured backup path 'c:\work\backup'.
java.io.FileNotFoundException: Source 'C:\Program Files (x86)\Jenkins\jobs\Build Job 1\builds\lastFailedBuild' does not exist
at org.apache.commons.io.FileUtils.copyDirectory(FileUtils.java:866)
at org.apache.commons.io.FileUtils.copyDirectory(FileUtils.java:814)
at org.jvnet.hudson.plugins.thinbackup.backup.HudsonBackup.backupBuildFiles(HudsonBackup.java:302)
at org.jvnet.hudson.plugins.thinbackup.backup.HudsonBackup.backupBuildsFor(HudsonBackup.java:270)
at org.jvnet.hudson.plugins.thinbackup.backup.HudsonBackup.backupJob(HudsonBackup.java:208)
at org.jvnet.hudson.plugins.thinbackup.backup.HudsonBackup.backupJobsDirectory(HudsonBackup.java:196)
at org.jvnet.hudson.plugins.thinbackup.backup.HudsonBackup.backupJobs(HudsonBackup.java:175)
at org.jvnet.hudson.plugins.thinbackup.backup.HudsonBackup.backup(HudsonBackup.java:142)
at org.jvnet.hudson.plugins.thinbackup.ThinBackupPeriodicWork.backupNow(ThinBackupPeriodicWork.java:87)
at org.jvnet.hudson.plugins.thinbackup.ThinBackupMgmtLink$1.execute(ThinBackupMgmtLink.java:76)
at org.jvnet.hudson.plugins.thinbackup.hudson.model.AsyncPeriodicWork$1.run(AsyncPeriodicWork.java:54)
at java.lang.Thread.run(Unknown Source)