diff -r af3bd9d1dbc1 -r 97cb1aeaca78 mercurial/cmdutil.py
--- a/mercurial/cmdutil.py	Thu Jun 11 23:04:14 2015 +0900
+++ b/mercurial/cmdutil.py	Fri Mar 04 14:44:32 2016 +0000
@@ -2212,7 +2212,7 @@
 def displaygraph(ui, repo, dag, displayer, edgefn, getrenamed=None,
                  filematcher=None):
     formatnode = _graphnodeformatter(ui, displayer)
-    seen, state = [], graphmod.asciistate()
+    state = graphmod.asciistate()
     for rev, type, ctx, parents in dag:
         char = formatnode(repo, ctx)
         copies = None
@@ -2230,7 +2230,7 @@
         if not lines[-1]:
             del lines[-1]
         displayer.flush(ctx)
-        edges = edgefn(type, char, lines, seen, rev, parents)
+        edges = edgefn(type, char, lines, state, rev, parents)
         for type, char, lines, coldata in edges:
             graphmod.ascii(ui, state, type, char, lines, coldata)
     displayer.close()