Ricardo Wurmus <rekado@elephly.net> writes:

> It is not fully automatic yet as it requires my input to stage
> hunks, but the commit messages it produces take all input changes into
> account, which is something the “update” yasnippet does not do.

Attached is the fully automatic version.

You just make your changes and run the tool.  It will stage all diffs
that are associated with the same S-expression, generate the commit
message, and make the commit for each S-expression.

Note that it probably doesn’t do the right thing when something other
than a package expression is modified (e.g. a copyright line).

-- 
Ricardo