CI Cannot cleanup workspace perhaps due to VirtIO issue

[Ananth Suryanarayana]

2015-01-14 01:27:59 + rm -rf /home/jenkins/workspace/ci-contrail-vrouter-unittest
2015-01-14 01:28:07 rm: cannot remove `/home/jenkins/workspace/ci-contrail-vrouter-unittest/repo': Directory not empty
2015-01-14 01:28:08 Build step 'Execute shell' marked build as failure

Many times, jobs fail because it cannot cleanup old disk space. Deletion is attempted by root, the super user.

https://jenkins.opencontrail.org/job/ci-contrail-web-controller-systest-ubuntu-precise-pangolin-havana/482/console

This has caused CI jobs to fail multiple times this adding to the agony. I strongly suspect issues with underlying VirtIO driver for issues like these..