Merge branch 'mm/push-default-switch-warning'

In the next major release, we will switch "git push [$there]" that does not say what to push from the traditional "matching" to the updated "simple" semantics, that pushes the current branch to the branch with the same name only when the current branch is set to integrate with that remote branch (all other cases will error out). * mm/push-default-switch-warning: push: start warning upcoming default change for push.default