By default clean up builds; previously some jobs didn't.

[itamarst]

We're running out of disk space, so make sure we clean up as much as possible.

[exarkun]

How much does this actually clean up? "Files owned by root" seems like a strange criterion to apply for cleanup. How about all the non-root owned files still taking up space? Presumably they'll eventually lead to an out-of-space condition too.

So maybe this it a good change, but it's hard to evaluate without knowing how much space it's going to save. But it's probably not sufficient to resolve the issue.

[exarkun]

But it's probably not sufficient to resolve the issue.

Therefore, clicking "changes requested".

[Azulinho]

looks like this one here:
https://wiki.jenkins-ci.org/display/JENKINS/Workspace+Cleanup+Plugin

[jml]

Can you please add a comment explaining why we don't want to clean the repo here?

[itamarst]

I have no idea, it was there when I got here.

[jml]

Failures look intermittent + FLOC-3564.

Please add the comment & merge when ready.