CI/Legalese: Require DCO (Signed-off-by: git tags) in commits

[jimklimov]

Closes: #1994

[rcrit]

This does not seem to be a common license. Fedora, for example, doesn't list it among its acceptable licenses. And does this mean there will be a triple license: GPLv2+, GPLv3+ and DCO?

[jimklimov]

Thanks for the question :)

This is not exactly an overall codebase license as such (a better filename is welcome), rather an acknowledged license grant by particular patch/PR author(s). They "sign off" (as inseparable part of their hashed git commit) an agreement that they contribute their piece of code to be used under the project's license (GPLv2+ in case of most of NUT; some other files and directories were borrowed elsewhere with their compatible licenses - see https://github.com/networkupstools/nut/blob/master/COPYING for details).

[jimklimov]

Anyhow, the GitHub org configuration was changed back when this was posted - so the PR just clarifies the rules in text. Merging of contributions is still up to maintainers, whether CI checks passed or not.