--- a/mercurial/commands.py	Mon Mar 13 11:03:59 2017 -0700
+++ b/mercurial/commands.py	Mon Mar 13 11:19:24 2017 -0700
@@ -2705,6 +2705,7 @@
     if not heads:
         return 1
 
+    ui.pager('heads')
     heads = sorted(heads, key=lambda x: -x.rev())
     displayer = cmdutil.show_changeset(ui, repo, opts)
     for ctx in heads: