Re: [PATCH] perf: work around the tested repo having an index.lock

[Junio C Hamano <gitster@pobox.com>]

Christian Couder <christian.couder@gmail.com> writes:

> On Sun, Jun 4, 2017 at 2:00 AM, Junio C Hamano <gitster@pobox.com> wrote:
>> Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:
>>
>>>> My feeling exactly.  Diagnosing and failing upfront saying "well you
>>>> made a copy but it is not suitable for testing" sounds more sensible
>>>> at lesat to me.
>>>
>>> This change makes the repo suitable for testing when it wasn't before.
>>
>> Perhaps "not suitable" was a bit too vague.
>>
>> The copy you made is not in a consistent state that is good for
>> testing.  This change may declare that it is now in a consistent
>> state, but removal of a single *.lock file does not make it so.  We
>> do not know what other transient inconsistency the resulting copy
>> has; it is inherent to git-unaware copy---that is why we discouraged
>> and removed rsync transport after all.
>
> If we don't like git-unaware copies, maybe we should go back to the
> reasons why we are making one here.

We do need git-unaware bit-for-bit copy for testing, because you may
want to see the effect of unreachable objects, for example.  

It's just that git-unaware copies, because it cannot be an atomic
snapshot, can introduce inconsistencies the original repository did
not have, rendering the result ineffective.