New minibuffer history for vc-user-edit-command (bug#80169)

* lisp/vc/vc-dispatcher.el (vc-user-edit-command-history): New variable.
(vc-user-edit-command): Use it (bug#80169).
* etc/NEWS: Announce it.

etc/NEWS

@@ -2885,6 +2885,11 @@ This command is Diff mode's specialized 'narrow-to-region'.
 consistency, 'diff-restrict-view' is now too.
 To enable it again, use 'M-x enable-command'.
 
+---
+*** 'C-x v !' has its own input history.
+This is shared with the input history of 'C-x v P' for certain backends
+which use the same mechanism as 'C-x v !'.
+
 ** Package
 
 +++

lisp/vc/vc-dispatcher.el

@@ -384,6 +384,9 @@ the man pages for \"torsocks\" for more details about Tor."
   :version "27.1"
   :group 'vc)
 
+(defvar vc-user-edit-command-history nil
+  "Minibuffer history for `vc-user-edit-command'.")
+
 (defun vc-user-edit-command (command file-or-list flags)
   "Prompt the user to edit VC command COMMAND and FLAGS.
 Intended to be used as the value of `vc-filter-command-function'."
@@ -398,7 +401,8 @@ Intended to be used as the value of `vc-filter-command-function'."
                             (cons command (remq nil (if files-separator-p
                                                         (butlast flags)
                                                       flags))))
-                           " ")))))
+                           " ")
+                   'vc-user-edit-command-history))))
     (list (car edited) file-or-list
           (nconc (cdr edited) (and files-separator-p '("--"))))))