Hi,
I changed the RPB qcom-lt builds to use docker-buster-amd64 because we have been experimenting image corruption with ext2simg tool in new RPB zeus builds [1], there is a related bug report [1] and that's the reason why our Debian builds uses img2simg.
I tried to use img2simg in Debian stretch but is an old version (5.x) and fails to create images when are small size (ramdisk).
So it's a good opportunity to change the docker builder to Debian buster with a newer img2simg (8.x) tool in qcom-lt builds, I made the change in a way that doesn't affect current builds that uses Debian stretch [3] and give time to other users to switch (if needed).
Regards,
Anibal