
When --offline is set elements should not revalidate cached data. The ubuntu element had not been updated to match this. SHA checking is also skipped as we only move a new cached file into place when the hash matches, and we might download a new hash before updating the image cache, which would cause persistent --offline failures. Change-Id: If1a0366b51951a73b7a3ffe23a29a3d910b08938
Use Ubuntu cloud images as the baseline for built disk images.
Overrides:
- To use a non-default URL for downloading base Ubuntu cloud images, use the environment variable DIB_CLOUD_IMAGES
- To download a non-default release of Ubuntu cloud images, use the environment variable DIB_RELEASE