Re: p2000 failure due to empty reflog

>
> On Mon, Oct 04 2021, Derrick Stolee wrote:
>
>> On 10/2/2021 1:37 PM, René Scharfe wrote:
>>> p2000 fails for me and reports:
>>>
>>>    perf 18 - git checkout -f - (full-v3):
>>>    running:
>>>    			(
>>>    				cd full-v3 &&
>>>    				echo >>f2/f4/a &&
>>>    				git checkout -f -
>>>    			)
>>>
>>>    error: pathspec '-' did not match any file(s) known to git
>>>
>>> checkout fails because the reflog is empty, so the "-" can't be
>>> resolved.  The pathspec error message is confusing, though.
>>>
>>> The patch below adds a reflog entry and allows the script to
>>> succeed.
>>>
>>> Before the "test_perf_on_all git commit -a -m A", there are two
>>> reflog entries in each of the five clones, after it there are
>>> none.  How is that even possible?
>>
>> That is certainly confusing. Is there something about your global
>> (or local to your test repo) GC settings that cause an auto-GC to
>> prune the reflog aggressively?
>
> Perhaps something to do with certain parts of the code doing a
> time(NULL), and other parts faking up times to be 2005-something?
>
> I have some WIP patches that run concurrent "git gc --auto" with a
> detach across the whole test suite, and IIRC I had to search/replace all
> time(NULL) with my own time() that faked up (looks it up) an epoch of
> 1113465166 to avoid this exact issue.
>
> If you try doing that across our tests I think you'll find that the
> @{-1} syntax (reflog-powered) will start failing.
>
> But that's from vague memory, but perhaps it'll point you in the right
> direction...