[gnome-sudoku] Add missing warning comment

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 0ad5e77b8a80959645f8a15170a1037f50adeff3
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Sun Oct 19 22:16:19 2014 -0500

    Add missing warning comment

 lib/sudoku-generator.vala |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/lib/sudoku-generator.vala b/lib/sudoku-generator.vala
index 1acdaba..0ae7c1e 100644
--- a/lib/sudoku-generator.vala
+++ b/lib/sudoku-generator.vala
@@ -28,6 +28,7 @@ public class SudokuGenerator : Object
         private int nsudokus;
         private DifficultyCategory level;
         // FIXME Require Gee.ConcurrentList and remove the mutex
+        // https://bugzilla.gnome.org/show_bug.cgi?id=737507
         private Gee.List<SudokuBoard> boards_list;
         private static Mutex mutex;
         private unowned SourceFunc callback;