Why legal checks before release?

Committing code to a version control system is a form of distribution,since it will be available to anyone. Distribution, in any form, is theusual trigger for copyright-based licenses, due to the nature ofcopyright in the law.

That's why we want the legal parts of the packaging job to be donebefore the package is approved at Savannah—notably includingvalid copyright notices and inclusion of the fulltext of your package license (ProjectApproval,HowToGetYourProjectApprovedQuickly).

In short, "release" in the legal sense is not only packaging a tarball.