Re: [PATCH] t9001: use a more distinct fake BugID

> In the test "cc list is sanitized", we feed a commit with a variety of
> trailers to send-email, and then check its output to see how it handled
> them. For most of them, we are grepping for a specific mention of the
> header, but there's a "BugID" header which we expect to be ignored. We
> confirm this by grepping for "12345", the fake BugID, and making sure it
> is not present.
> 
> But we can be fooled by false positives! I just tracked down a flaky
> test failure here that was caused by matching this unrelated line in the
> output:
> 
>   <20240914090449.612345-1-author@example.com>
> 
> which will change from run to run based on the time, pid, etc.
> 
> Ideally we'd tighten the regex to make this more specifically, but since
> the point is that it _shouldn't_ be mentioned, it's hard to say what the
> right match would be (e.g., would there be a leading space?).
> 
> Instead, let's just choose a match that is much less likely to appear.
> The actual content of the header isn't important, since it's supposed to
> be ignored.
> 
> Signed-off-by: Jeff King <peff@peff.net>
> ---
> I guess this is fairly unlikely, as re-running the test with --stress
> didn't reproduce after a few hundred attempts. Back of the envelope, I
> guess any 5-digit sequence has a 1-in-10^5 chance of matching our
> target. There are 2 in chances in a 6-digit pid. Some in the date, but
> as there's no December 34th or hour 34, you're limited to a few specific
> times like 01:23:45 (or at 11am), 12:34:5x, or perhaps 23:45 on the 1st,
> 11th, or 21st of the month.
> 
> So I think I just got really unlucky, but after spending several minutes
> debugging, I wouldn't want to wish it on anybody else. ;)