Comment 0 for bug 1616831

Trying to use the new configuration format of APT configuration while still providing the OLD format, causes cloud-init fails to configure APT.

cloud-init should be ignoring the old format if the new format is provided to ensure backwards compat.

This is a problem for MAAS provided that we cannot safely differentiate / determine what cloud-init version we are using for a specific release we are deploying, and as such, we still need to send the old config while still providing the new one because:

1. Yakkety uses newer cloud-init with new format above
2. Xenial, Trusty, Precise use older cloud-init that doesn't support new format.

And this is a problem because:

1. MAAS won't be able to use derived repositories in Xenial, Trusty, Precise until this gets backported into cloud-init.
2. Commission is done in Xenial, while deployment in Yakkety, but both may require the same config, but it is only supported in Yakkety's cloud-init.
3. Users may be using old images that may not contain new cloud-init at all, and even though the release already supports it, the image they are using doesn't and they have to continue to use the old format.
4. MAAS cannot differentiate/identify which cloud-init version its being used, as such, needs to sends both old and new config.