38.2.1. You must put some 'source' URIs in your sources.list
If ./build --download-dependencies fails with:
E: You must put some 'source' URIs in your sources.list
see this: https://askubuntu.com/questions/496549/error-you-must-put-some-source-uris-in-your-sources-list/857433#857433 I don’t know how to automate this step. Why, Ubuntu, why.