I saw several of these yesterday. Most recent example from today: https://build.gluster.org/job/netbsd6-smoke/18607/console It looks like files are being deleted while the build is still in progress. In the past this has been the result of multiple simultaneous runs using the same workspace. I was able to work around it by ensuring that netbsd-smoke was only running on one of my patches at a time (nobody else was submitting patches at the time), further suggesting this is the case.
Another example: https://build.gluster.org/job/netbsd6-smoke/18609/console
Okay, I can reproduce this. I'm going to disable netbsd6-smoke until we can figure out what's going wrong.
Narrowed this down to my mistake. I set both machines in Jenkins to have different names but point to the same IP. I hadn't noticed my error until last night when I checked if the configuration was correct on both servers. This has been fixed up and the job re-enabled.