When myjob start build, I'll see the "File already exists"  IOException in jenkins log, such as:

 WARNING h.p.t.TimestamperBuildWrapper$ConsoleLogFilterImpl#decorateLogger: File already exists: ${jenkins_home}/jobs/${myjob}/builds/204/timestamper/timestamps
java.io.IOException: File already exists: ${jenkins_home}/jobs/${myjob}/builds/204/timestamper/timestamps
at hudson.plugins.timestamper.io.TimestampsWriter.<init>(TimestampsWriter.java:86)
at hudson.plugins.timestamper.TimestamperBuildWrapper$ConsoleLogFilterImpl.decorateLogger(TimestamperBuildWrapper.java:114)
at jenkins.tasks.SimpleBuildWrapper.decorateLogger(SimpleBuildWrapper.java:193)
at hudson.maven.MavenBuild$ProxyImpl2.<init>(MavenBuild.java:600)
at hudson.maven.MavenModuleSetBuild$MavenModuleSetBuildExecution.doRun(MavenModuleSetBuild.java:733)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:514)
at hudson.model.Run.execute(Run.java:1894)
at hudson.maven.MavenModuleSetBuild.run(MavenModuleSetBuild.java:543)
at hudson.model.ResourceController.execute(ResourceController.java:97)
at hudson.model.Executor.run(Executor.java:428)

in the old jenkins server (jenkins 2.120, timestamper 1.8.9) has no this exception