--- a/hgext/evolve.py	Thu Apr 14 15:02:10 2016 +0000
+++ b/hgext/evolve.py	Thu Apr 14 15:03:18 2016 +0000
@@ -1876,8 +1876,8 @@
         if not pctx.obsolete():
             pctx = orig.p2()  # second parent is obsolete ?
         elif orig.p2().obsolete():
-            hint = _("Redo the merge and use `hg prune <old> "
-                     "--succ <new>` to obsolete the old one")
+            hint = _("Redo the merge (%s) and use `hg prune <old> "
+                     "--succ <new>` to obsolete the old one") % orig.hex()[:12]
             ui.warn(_("warning: no support for evolving merge changesets "
                       "with two obsolete parents yet\n") +
                     _("(%s)\n") % hint)