Looking at this excellent OUR post https://our.umbraco.org/forum/umbraco-7/using-umbraco-7/60675-Alter-default-Save-button which includes a code sample to change Umbraco/Js/umbraco.services.js so you can have "Save" as default instead of "Publish" (my customer's current requirement)

& reading this really excellent Matt Brailsford post https://24days.in/umbraco-cms/2015/umbraco-7-back-office-tweaks/ from a little while ago. Here he proposes using something like:

$httpProvider.interceptors.push(function ($q) {

I'm trying to combine the two and inject this change rather than alter the source of a file that would get replaced in an upgrade.

Am I missing the point though? Does this mean I have to copy and inject the whole function or can I somehow inject just this change?

I'm thinking that I'd need to copy the whole contentEditingHelper service there's a reasonable risk that any future update may actually require a change in this to work so the whole thing might be self-defeating. A second opinion on another way to do this would be good.