Kévin Le Gouguec <kevin.legouguec@gmail.com> writes:

>> How about just ignoring the error in this case?  AFAIU, it's rare
>> enough to not be important, right?  AFAIK, you cannot have more than
>> one Git instance modifying the repository at any given time, so this
>> problem cannot be fixed in principle if we are running tow or more Git
>> sessions in parallel.  IOW, these tests must NOT be run via parallel
>> make processing.
>
> Apologies if my brain is too fried and I misunderstood: didn't I show
> that this error shows up without parallelism?
>
>   $ while make -j1 -C test lisp/vc/vc-git-tests ; do continue ; done
[… snip demo …]
>
>
> At any rate, to hopefully contribute something to the discussion if I
> misunderstood your comment: given the goals of this test, wondering if
> it would be acceptable to have it invoke vc-git-dir-extra-headers
> directly, instead of "pretending to be a user" and invoking vc-dir.  If
> vc-dir is indeed responsible for whatever async process is thwarting
> that test, cutting that middle man out would work around that (and let
> us remove some scaffolding from the test to boot).

Attaching what I have in mind (including an --ignore-all-space variant).
Mainly FTR and to clarify my yammering ; ATM it is not clear that it
solves the problem.  (≈3k iterations in 12min and counting; 🤞 but I had
to wait an actual hour once or twice to reproduce the error…)

> (If Git is responsible for that async process, then that change alone
> will not help, although the scaffolding simplification would still be
> nice TBH)