"simple" vs "current" push.default in git for decentralized workflow

The difference is that with simple, git push (without passing a refspec) will fail if the current branch isn't tracking a remote upstream branch (even if a branch with the same name exists on the remote):

$ git checkout -b foo
Switched to a new branch 'foo'

$ git config push.default simple
$ git push
fatal: The current branch foo has no upstream branch.
To push the current branch and set the remote as upstream, use

    git push --set-upstream origin foo

On the other hand, current doesn't care about whether or not the current branch tracks an upstream, it just wants to push to any branch that has the same name:

$ git config push.default current
$ git push
Total 0 (delta 0), reused 0 (delta 0)
To /Documents/GitHub/bare
 * [new branch]      foo-> foo

The Documentation

From the Git configuration documentation:

• upstream - push the current branch to its upstream branch...

• simple - like upstream, but refuses to push if the upstream branch’s name is different from the local one...

• current - push the current branch to a branch of the same name.

The difference is that simple pushes to its tracking branch if it has the same name, while current will push to a branch of the same name regardless of any tracking branch:

$ git branch -vvv
  master 58d9fdc [origin/master: ahead 1] t1 bobo
* new    37132d3 [origin/save: ahead 1] t1 bibi   # <- tracking branch 'save'

$ git -c push.default=current push                # <- set `push.default=current`
Counting objects: 3, done.
Writing objects: 100% (3/3), 234 bytes | 0 bytes/s, done.
Total 3 (delta 0), reused 0 (delta 0)
To /home/jthill/sandbox/20/t1
 * [new branch]      new -> new                   # <- and push creates `new`