The images produced by the diskimage-builder have their filesystem with a label of "cloudimg-rootfs", so we need to change the default /etc/fstab on fedora to reflect that. Change-Id: Id1bb00cb81cb200a114f500e26272624be577da0
Use Fedora cloud images as the baseline for built disk images.
Overrides:
- To use a non-default URL for downloading base Fedora cloud images, use the environment variable DIB_CLOUD_IMAGES
- To download a non-default release of Fedora cloud images, use the environment variable DIB_RELEASE