Re: emacs-31 a9fc13614ec: Export GIT_OPTIONAL_LOCKS=0 for "git status" invocations (bug#80903)

Eli Zaretskii [01/Aug  9:06am +03] wrote:
>> From: [email protected]
>> Date: Fri, 31 Jul 2026 12:00:15 -0400
>>
>> branch: emacs-31
>> commit a9fc13614eca8aaa34d227b28c4c4d37b13212af
>> Author: Sean Whitton <[email protected]>
>> Commit: Sean Whitton <[email protected]>
>>
>>     Export GIT_OPTIONAL_LOCKS=0 for "git status" invocations (bug#80903)
>>
>>     * lisp/vc/vc-git.el (vc-git--env-vars): New function.
>>     (vc-git-command, vc-git--call): Use it (bug#80903).
>> ---
>>  lisp/vc/vc-git.el | 39 +++++++++++++++++++--------------------
>>  1 file changed, 19 insertions(+), 20 deletions(-)
>>
>> diff --git a/lisp/vc/vc-git.el b/lisp/vc/vc-git.el
>> index f336aae984d..17c358e25d5 100644
>> --- a/lisp/vc/vc-git.el
>> +++ b/lisp/vc/vc-git.el
>> @@ -2884,6 +2884,21 @@ page for the meanings of these attributes."
>>  
>>  ;;; Internal commands
>>
>> +(defun vc-git--env-vars (subcommand)
>> +  "Return env vars for the `process-environment' of Git processes."
>> +  `("GIT_DIR"
>> +    ,@(and vc-git-use-literal-pathspecs
>> +           '("GIT_LITERAL_PATHSPECS=1"))
>> +    ;; Avoid optional repository locking during background operations
>> +    ;; (bug#21559, bug#80903).  Skipping these locks is always safe and
>> +    ;; can only lead to subsequent commands running more slowly.
>> +    ;; The "git status" case covers how `vc-checkin' uses
>> +    ;; `vc-dir-resynch-file' to update the display state of files
>> +    ;; undergoing an asynchronous check-in.
>> +    ,@(and (or revert-buffer-in-progress
>> +               (equal subcommand "status"))
>> +           '("GIT_OPTIONAL_LOCKS=0"))))
>
> GIT_OPTIONAL_LOCKS is supported only since Git 2.15.  Would it be
> possible to use the --no-optional-locks command-line option instead?

That would be a riskier change because setting an env var doesn't
disrupt the rest of argument parsing, as compared with passing a new
argument.

Git 2.15 is almost nine years old.  Perhaps it's okay if asynchronous
check-ins (an optional feature) occasionally fail due to a race?

-- 
Sean Whitton