Precommit builds stuck due to no nodes

[Josh Elser]

It would appear that Precommit builds are hung due to having no 
available Jenkins nodes to execute the jobs on. I'm guessing this has to 
do with Infra's recent re-working of some of the worker node labels.

Just an FYI that I'm looking into it and I'll send a note when I get a 
resolution in place.

- Josh

https://builds.apache.org/label/(ubuntu&&Hadoop)&&!jenkins-cloud-4GB/