Because of our caching feature, fromager only downloads the source if the wheel does not exist in the cache or if the wheel does exist in cache but does not contain the info for required to extract the build deps. So when the onboarder tries to upload the sdist of a package that existed in cache, it is not able to find it and ends up erroring out.

If this happens the onboarder can still download the sdist from the information in the build-order file