Reset beta to master (while keeping history)

This is done by this series of commands
1. git checkout master
2. git checkout -b tmp # Creates a temporary branch at the head of master
3. git merge -s ours beta # Discards all changes from beta
4. git checkout beta
5. git reset --hard tmp # Sets beta HEAD to the merged HEAD
6. git branch -d tmp
(Optional)
7. git commit --amend # To improve the commit message