/var/lib/libvirt/images gets filled on isobuilders

On isobuilder3, right now:

total 2.8G
drwx------ 2 root         root          16K May  9 14:04 lost+found/
-rwxr--r-- 1 libvirt-qemu libvirt-qemu 741M May 25 16:45 tails-builder-amd64-jessie-20170510-d6ed806417_vagrant_box_image_0.img*
-rw------- 1 libvirt-qemu libvirt-qemu 1.3G May 25 18:27 tails-builder-amd64-jessie-20170524-8cc1ccbade_default.img
-rwxr--r-- 1 libvirt-qemu libvirt-qemu 743M May 25 17:37 tails-builder-amd64-jessie-20170524-8cc1ccbade_vagrant_box_image_0.img*

… while https://jenkins.tails.boum.org/job/reproducibly_build_Tails_ISO_feature-stretch/22/console is running.

Feature Branch: bugfix/12599-rake-task-removing-tails-builder-volumes,jenkins-jobs:bugfix/12599-rake-task-removing-tails-builder-volumes

Parent Task: #12531 (closed)

Related issues

• Related to #12579 (closed)
• Related to #12002 (closed)
• Related to #13302 (closed)
• Blocks #12637 (closed)

Original created by @intrigeri on 12599 (Redmine)