I attempted to install this plugin and I get this error.

java.io.IOException: Failed to download from http://updates.jenkins-ci.org/download/plugins/scm-sync-configuration/0.0.7.4/scm-sync-configuration.hpi
at hudson.model.UpdateCenter$UpdateCenterConfiguration.download(UpdateCenter.java:781)
at hudson.model.UpdateCenter$DownloadJob._run(UpdateCenter.java:1125)
at hudson.model.UpdateCenter$InstallationJob._run(UpdateCenter.java:1285)
at hudson.model.UpdateCenter$DownloadJob.run(UpdateCenter.java:1103)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
at java.util.concurrent.FutureTask.run(FutureTask.java:166)
at hudson.remoting.AtmostOneThreadExecutor$Worker.run(AtmostOneThreadExecutor.java:104)
at java.lang.Thread.run(Thread.java:701)
Caused by: java.io.IOException: Server returned HTTP response code: 503 for URL: http://updates.jenkins-ci.org/download/plugins/scm-sync-configuration/0.0.7.4/scm-sync-configuration.hpi
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)