Fix for issue 1706. (issue4662047)

[mtsolo]

Reviewers: ,

Message:
I think this'll do it.

Cheers,
MS

Description:
Fix for issue 1706.

Please review this at http://codereview.appspot.com/4662047/

Affected files:
  M lily/beam.cc


Index: lily/beam.cc
diff --git a/lily/beam.cc b/lily/beam.cc
index  
8a30752c386eccd8294b181c5dd18159c2b492d2..e9ab3540b62318c1426f72bf36d2bdd008119482  
100644
--- a/lily/beam.cc
+++ b/lily/beam.cc
@@ -555,6 +555,8 @@ Beam::print (SCM grob)
   Spanner *me = unsmob_spanner (grob);
   Grob *commonx = 0;
   vector<Beam_segment> segments = get_beam_segments (me, &commonx);
+  if (!segments.size ())
+    return SCM_EOL;

   Interval span;
   if (normal_stem_count (me))
@@ -974,7 +976,7 @@ Beam::no_visible_stem_positions (Grob *me, Interval  
default_value)
     }

   Direction dir = get_grob_direction (me);
-  Real y = head_positions[dir]
+  Real y = head_positions[dir ? dir : UP]
     * 0.5 * Staff_symbol_referencer::staff_space (me)
     + dir * get_beam_translation (me) * (multiplicity.length () + 1);