If you run devtool modify -x / devtool extract, we rely on logic in patch.bbclass to try to produce reasonable commits in the resulting git repository for patches applied by the recipe that aren't directly applicable with git am. If we're missing information however (author, date, possibly even header message) then it would be worth trying to extract these from the commit that added the patch in the first place; at the moment we just use the current date and the user's default author which may sometimes be a bit confusing.