Felipe Contreras wrote:

== git update ==

Another proposed solution is to have a new command: `git update`. This
command would be similar to `git pull --ff-only` by default, but it
could be configured to do merges instead, and when doing so in reverse.

And here it is:

https://github.com/felipec/git/commits/fc/update

Here's the documentation:

https://github.com/felipec/git/wiki/git-update

Works exactly as expected: non-fast-forwards are rejected by default,
but can be configured, and parents are reversed when merging.

-- 
Felipe Contreras