My recommendation:

• Stick the 6.1.5 iso and source zip file in the Every-D.eSystem-version repo that you already have for historical releases.
• Delete the all_D.eSystem_versions repo.
• When you’re ready to make a 6.1.6 release, make a new repo named D.eSystem.
• Update the readme in the Every-D.eSystem-version to indicate it won’t house any version greater than 6.1.5 and link to the D.eSystem repo for newer versions.
• Push the 6.1.6 version of your codebase to the D.eSystem repo as the initial commit.
• Tag that initial commit in the D.eSystem repo 6.1.6.
• Make a new release in the D.eSystem repo referencing the 6.1.6 tag.
• Thereafter, follow atomic commit practices. But even if you don’t follow atomic commit practices, don’t make new releases without pushing the version of the code from which you built the release to your D.eSystem repo and tagging the exact commit you build the release off of.

There are all kinds of more advanced topics in the field of release management like https://en.wikipedia.org/wiki/Reproducible_builds and nightly builds and automated test suite running and such. But the above will solve the immediate problems.