Belief: The pull request broke the search field auto focus.
Truth: The pull request did break it. There was an additional reason beyond the pull request unknown to the author, but that's not important to the Truth portion here.
Justified: This is the only one you can really debate on, just as philosophers have for a long time. Was he justified in his belief that he broke autofocus? I think so based on the original JTB definition since there is clear evidence that the pull request directly led to the break rather than some other event.
I think that when claiming it's not a JTB you're choosing to focus on the underlying (hidden) issue(s) rather than what the author was focusing on, which is kind of the whole point of Gettier's original cases. For example Case I's whole point is that facts unknown to Smith invalidate his JTB. In this programming example, facts unknown to the author (that someone else introduced a bug in their framework update) invalidate his JTB as well.