I thought that the 1.8.0-dev changes are in News file, and that what is new for 1.7.0 are on History. I think It’s as you say untill the beta-release. Then, everything in News have been moved to History. Now History points to 1.8.0-dev. Maybe I’m wrong. Sorry if that’s the case.
UPDATE: Sorry, I was pointing to master branch on which what’s on NEWS.md is now on HISTORY.md.