Description
As of 85414d8 we're missing the "{user} referenced this issue {date}" backlinks that github creates when another issue references the current one. I'll link this issue to #3134 and vice versa so both show an example of what these should look like -- see below.
These links are pretty important; they turn github issues from disjoint threads into an interlinked, multi-threaded mesh. They help to prevent and converge duplicates, and probably have a role in community-building.
In my own case, as soon as we had created more than a few issues and users in our local Gitea install, I immediately started wanting these backlinks. This is the sort of problem that #1029 exposes.
I'm trying to figure out the right way to tackle this; do we somehow detect and create the backlinks on the fly as we render the HTML? Or do we use a backlinks table that gets populated as the references are created? If the latter, we would want to scan through existing comments at migration to create the initial table content when upgrading from older versions, right?