Issue 4212: fix out-of-bounds index in division_maior() (issue 189420043 by address@hidden)

[nine . fierce . ballads]

Reviewers: ,

Description:
Issue 4212: fix out-of-bounds index in division_maior()

Please review this at https://codereview.appspot.com/189420043/

Affected files (+1, -1 lines):
  M lily/breathing-sign.cc


Index: lily/breathing-sign.cc
diff --git a/lily/breathing-sign.cc b/lily/breathing-sign.cc
index  
2cbe20e303d9318bfc3eaeb103f0ae946e731b11..6ec306dde461fbc8a70878d86f178700284e1eaa  
100644
--- a/lily/breathing-sign.cc
+++ b/lily/breathing-sign.cc
@@ -119,7 +119,7 @@ Breathing_sign::divisio_maior (SCM smob)
                                     ydim[DOWN]);
               assert (line_pos.begin () < it);
               double val = (it[-1] + it[0]) / 2;
-              if (ydim[DOWN] < val && line_pos.begin () < it + 1)
+              if (ydim[DOWN] < val && line_pos.begin () < it - 1)
                 val = (it[-2] + it[-1]) / 2;
               ydim.add_point (val);