For the record in case it's useful, the commit that broke this is https://hg.mozilla.org/integration/autoland/rev/90c803e44a4a according to git bisect.
Bug 1768241 Comment 3 Edit History
Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.
For the record in case it's useful, the commit that broke this is https://hg.mozilla.org/mozilla-central/rev/22b568631834e556ab8351ac8458d5b24aa638bd according to git bisect.