The GIT branch 5.0 has just been created for Kamailio source tree, it will host the release series 5.0.x. To get this branch from GIT, you can use:
git clone https://github.com/kamailio/kamailio.git kamailio cd kamailio git checkout -b 5.0 origin/5.0
Hopefully before the end of the month the full release of 5.0.0 will be out.
From now on, any corresponding fix has to be pushed first to master branch and then cherry-picked to branch 5.0. No new features can get in branch 5.0. Enhancements to documentation or helping tools are still allowed.
Thanks for flying Kamailio!