Re: [PATCH] t5512.40 sometimes dies by SIGPIPE

> The last test in t5512 we recently added seems to be flaky.
> Running
>
>     $ make && cd t && sh ./t5512-ls-remote.sh --stress
>
> shows that "git ls-remote foo::bar" exited with status 141, which
> means we got a SIGPIPE.  This test piece was introduced by 9e89dcb6
> (builtin/ls-remote: fall back to SHA1 outside of a repo, 2024-08-02)
> and is pretty much independent from all other tests in the script
> (it can even run standalone with everything before it removed).
>
> The transport-helper.c:get_helper() function tries to write to the
> helper.  As we can see the helper script is very short and can exit
> even before it reads anything, when get_helper() tries to give the
> first command, "capabilities", the helper may already be gone.
>
> A trivial fix, presented here, os to make sure that the helper reads

> the first command it is given, as what it writes later is a response
> to that command.
>
> I however would wonder if the interactions with the helper initiated
> by get_helper() should be done on a non-blocking I/O (we do check
> the return value from our write(2) system calls, do we?).
>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>