[gnome-sudoku/gnome-3-14] Workaround 100% CPU usage issue

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 12fac1e134482e25b0342d1607d347509cd33756
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Sat Oct 4 16:45:05 2014 -0500

    Workaround 100% CPU usage issue
    
    No clue what's going wrong here....
    
    https://bugzilla.gnome.org/show_bug.cgi?id=737507

 lib/sudoku-generator.vala |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/lib/sudoku-generator.vala b/lib/sudoku-generator.vala
index b6cb145..7dcb036 100644
--- a/lib/sudoku-generator.vala
+++ b/lib/sudoku-generator.vala
@@ -45,7 +45,8 @@ public class SudokuGenerator : Object
 
     public async static SudokuBoard[] generate_boards_async (int nboards, DifficultyCategory category) 
throws ThreadError
     {
-        var boards_list = new ConcurrentList<SudokuBoard> ();
+// FIXME broken: not threadsafe!
+        var boards_list = new ArrayList<SudokuBoard> ();
         var boards = new SudokuBoard[nboards];
         var threads = new ArrayList<Thread<void*>> ();