If you have a slave node that goes offline when idle that holds the workspace of a build, any GitHub push automatically triggers a build with the message:

Started on May 24, 2013 8:15:43 PM
Workspace is offline.
Scheduling a new build to get a workspace. (nonexisting_workspace)
Done. Took 1 ms
Changes found

Two issues here:

1. If the job is triggered by a "Test Hook" call from GitHub and the slave is offline, it was always make a build job even if the there isn't any changes.
2. (unconfirmed but very likely) The job would build even if the branch it is supposed to build isn't the one that was updated because of the "nonexisting_workspace" error.

This could be resolved if all the tracking took place on the master node.

Thank you for your consideration.