Activate range-diff feature of triagebot

[samueltardieu]

This feature shows the changes when a PR is rebased, while the GitHub UI would mix the actual changes with the ones coming from the rebase.

changelog: none

r? @flip1995

[flip1995]

Do you have an example from another repo how this looks like. This sounds like it could get quite spammy for people that use a rebase workflow.

[samueltardieu]

The compiler uses it. For example, this comment gives a link which shows that only a one-line change occurred during the rebase, while GitHub's provided "Compare" (just above the comment I linked) shows all the changes that happened between both bases as well.

For me, not having a range-diff when reviewing patches make the process a bit more complicated. For example, one of our most active contributors tends to react to reviews by adding new commits, which is fine. When I ask them to squash them when it's time to merge, they also tend to rebase the squashed commits onto the current master at the same time. As a consequence, I have to check manually every time that no changes other than squashing and rebasing occurred, while using the range-diff would show no change at all apart from rebasing, and would not require me to ask the contributor to change their process either.

[flip1995]

Yeah, I definitely can see that this is useful. GitHub is kinda bad at diffing rebases... Not sure why, all other platforms (gitlab, graphite, ...) seem to have figured it out 🤷

Let's merge this then and see if someone complains.