Show mentions next to comments

[mal-tee]

E.g. datenanfragen/data#2817

[baltpeter]

@mal-tee Not quite sure what you mean. Unless I'm missing something, there were no mentions in the PR you linked?

And a test comment I made with a mention looks like it's displaying correctly to me:

[mal-tee]

Oh, sorry. I really have to be more verbose in issues. I think I meant references, e.g. datenanfragen/data#2818 references datenanfragen/data#2817

[baltpeter]

Oh, these!

[baltpeter]

We can get these using the timeline events API (event: cross-referenced), e.g.: https://api.github.com/repos/datenanfragen/data/issues/2817/timeline