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

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"))))
+
 (defun vc-git-command (buffer okstatus file-or-list &rest flags)
   "A wrapper around `vc-do-command' for use in vc-git.el.
 The difference to `vc-do-command' is that this function always invokes
@@ -2903,16 +2918,8 @@ The difference to `vc-do-command' is that this function always invokes
          ;; want to do it only for commands which really require it.
 	 (coding-system-for-write
           (or coding-system-for-write vc-git-commits-coding-system))
-         (process-environment
-          (append
-           `("GIT_DIR"
-             ,@(and vc-git-use-literal-pathspecs
-                    '("GIT_LITERAL_PATHSPECS=1"))
-             ;; Avoid repository locking during background operations
-             ;; (bug#21559).
-             ,@(and revert-buffer-in-progress
-                    '("GIT_OPTIONAL_LOCKS=0")))
-           process-environment))
+         (process-environment (append (vc-git--env-vars (car flags))
+                                      process-environment))
          (file1 (and (not (cdr-safe file-or-list))
                      (or (car-safe file-or-list) file-or-list)))
          (file-list-is-rootdir (and file1
@@ -2954,16 +2961,8 @@ The difference to `vc-do-command' is that this function always invokes
          (or coding-system-for-read vc-git-log-output-coding-system))
 	(coding-system-for-write
          (or coding-system-for-write vc-git-commits-coding-system))
-	(process-environment
-	 (append
-	  `("GIT_DIR"
-            ,@(when vc-git-use-literal-pathspecs
-                '("GIT_LITERAL_PATHSPECS=1"))
-	    ;; Avoid repository locking during background operations
-	    ;; (bug#21559).
-	    ,@(when revert-buffer-in-progress
-		'("GIT_OPTIONAL_LOCKS=0")))
-	  process-environment)))
+	(process-environment (append (vc-git--env-vars command)
+                                     process-environment)))
     (apply #'process-file vc-git-program infile buffer nil
            "--no-pager" command args)))