master acc6732ca1d: Reuse commit message when preparing a single patch

[Philip Kaludercic]

branch: master
commit acc6732ca1d39352f1aae3074ad04564178c0954
Author: Philip Kaludercic <philipk@posteo.net>
Commit: Philip Kaludercic <philipk@posteo.net>

    Reuse commit message when preparing a single patch
    
    * lisp/vc/vc.el (vc-prepare-patch): Check commit message if only
    a single revision was selected.
---
 lisp/vc/vc.el | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/lisp/vc/vc.el b/lisp/vc/vc.el
index ca6efeabac2..619b469bebb 100644
--- a/lisp/vc/vc.el
+++ b/lisp/vc/vc.el
@@ -3623,7 +3623,15 @@ revisions.
 When invoked interactively in a Log View buffer with
 marked revisions, use those."
   (interactive
-   (let ((revs (vc-prepare-patch-prompt-revisions)) to)
+   (let* ((revs (vc-prepare-patch-prompt-revisions))
+          (subject
+           (and (length= revs 1)
+                (plist-get
+                 (vc-call-backend
+                  (vc-responsible-backend default-directory)
+                  'prepare-patch (car revs))
+                 :subject)))
+          to)
      (require 'message)
      (while (null (setq to (completing-read-multiple
                             (format-prompt
@@ -3636,7 +3644,7 @@ marked revisions, use those."
        (sit-for blink-matching-delay))
      (list (string-join to ", ")
            (and (not vc-prepare-patches-separately)
-                (read-string "Subject: " "[PATCH] " nil nil t))
+                (read-string "Subject: " (or subject "[PATCH] ") nil nil t))
            revs)))
   (save-current-buffer
     (let ((patches (mapcar (lambda (rev)