New command log-view-copy-revision-as-kill

* lisp/vc/log-view.el (log-view-copy-revision-as-kill): New
command.
(log-view-mode-map): Bind it.
* doc/emacs/maintaining.texi (VC Change Log):
* etc/NEWS: Document it.

doc/emacs/maintaining.texi

@@ -1244,6 +1244,11 @@ Display the changeset diff between the revision at point and the next
 earlier revision (@code{log-view-diff-changeset}).  This shows the
 changes to all files made in that revision.
 
+@item w
+Copy the revision of the marked log entries into the kill ring, as if
+you had killed them with @kbd{M-w}.  Multiple entries will be separated
+by a space.
+
 @item @key{RET}
 In a compact-style log buffer (e.g., the one created by @kbd{C-x v L}),
 toggle between showing and hiding the full log entry for the revision at

etc/NEWS

@@ -2393,6 +2393,13 @@ You can get back the old behavior with something like this:
 
 In addition, a new command 'U' removes all marks.
 
+---
+*** A new command 'log-view-copy-revision-as-kill' added.
+The new 'log-view-copy-revision-as-kill' command copies the revision of
+the log entry at point to the kill-ring.  When multiple log entries are
+marked the command copies all revisions in a single space separated
+string.  The command is bound by default to `w' in log-view-mode-map.
+
 ** Diff mode
 
 +++

lisp/vc/log-view.el

@@ -136,6 +136,7 @@
   "f" #'log-view-find-revision
   "n" #'log-view-msg-next
   "p" #'log-view-msg-prev
+  "w" #'log-view-copy-revision-as-kill
   "TAB" #'log-view-msg-next
   "<backtab>" #'log-view-msg-prev)
 
@@ -749,6 +750,18 @@ considered file(s)."
                log-view-vc-fileset)))
      fr to)))
 
+(defun log-view-copy-revision-as-kill ()
+  "Copy the revision under point, as a string, to the `kill-ring'."
+  (interactive)
+  (let ((revisions (log-view-get-marked)))
+    (if (length> revisions 1)
+        (let ((found (string-join revisions " ")))
+          (kill-new found)
+          (message "%s" found))
+      (when-let* ((rev (or (car revisions) (cadr (log-view-current-entry)))))
+        (kill-new rev)
+        (message "%s" rev)))))
+
 (provide 'log-view)
 
 ;;; log-view.el ends here