Only show "2x entries" i vc log buffers if needed

* lisp/vc/vc.el (vc-print-log-setup-buttons): Only show the "more"
buttons if we got more or equal to the number of entries we asked
for (bug#18959).

1 files changed, 27 insertions, 15 deletions

diff --git a/lisp/vc/vc.el b/lisp/vc/vc.el
index 6c96d8ca7c4..bc9f11202b1 100644
--- a/lisp/vc/vc.el
+++ b/lisp/vc/vc.el
@@ -2392,6 +2392,7 @@ If it contains `file', show short logs for files.
 Not all VC backends support short logs!")
 
 (defvar log-view-vc-fileset)
+(defvar log-view-message-re)
 
 (defun vc-print-log-setup-buttons (working-revision is-start-revision limit pl-return)
   "Insert at the end of the current buffer buttons to show more log entries.
@@ -2401,21 +2402,32 @@ Does nothing if IS-START-REVISION is non-nil, or if LIMIT is nil,
 or if PL-RETURN is `limit-unsupported'."
   (when (and limit (not (eq 'limit-unsupported pl-return))
 	     (not is-start-revision))
-    (goto-char (point-max))
-    (insert "\n")
-    (insert-text-button "Show 2X entries"
-                        'action (lambda (&rest _ignore)
-                                  (vc-print-log-internal
-                                   log-view-vc-backend log-view-vc-fileset
-                                   working-revision nil (* 2 limit)))
-                        'help-echo "Show the log again, and double the number of log entries shown")
-    (insert "    ")
-    (insert-text-button "Show unlimited entries"
-                        'action (lambda (&rest _ignore)
-                                  (vc-print-log-internal
-                                   log-view-vc-backend log-view-vc-fileset
-                                   working-revision nil nil))
-                        'help-echo "Show the log again, including all entries")))
+    (let ((entries 0))
+      (goto-char (point-min))
+      (while (re-search-forward log-view-message-re nil t)
+        (cl-incf entries))
+      ;; If we got fewer entries than we asked for, then displaying
+      ;; the "more" buttons isn't useful.
+      (when (>= entries limit)
+        (goto-char (point-max))
+        (insert "\n")
+        (insert-text-button
+         "Show 2X entries"
+         'action (lambda (&rest _ignore)
+                   (vc-print-log-internal
+                    log-view-vc-backend log-view-vc-fileset
+                    working-revision nil (* 2 limit)))
+         'help-echo
+         "Show the log again, and double the number of log entries shown")
+        (insert "    ")
+        (insert-text-button
+         "Show unlimited entries"
+         'action (lambda (&rest _ignore)
+                   (vc-print-log-internal
+                    log-view-vc-backend log-view-vc-fileset
+                    working-revision nil nil))
+         'help-echo "Show the log again, including all entries")
+        (insert "\n")))))
 
 (defun vc-print-log-internal (backend files working-revision
                                       &optional is-start-revision limit type)