[gcompris] Fix bug: mining-activity: level start nugget hide

[Bruno Coudoin <bcoudoin src gnome org>]

commit 77b81de0c0a9a4fbfc7eff3f0385e8fa6bc00a09
Author: Peter Albrecht <pa-dev gmx de>
Date:   Sat Sep 15 20:42:31 2012 +0200

    Fix bug: mining-activity: level start nugget hide
    
    When the user manually changes the level, the new nugget should be
    placed hidden. This was not the case, if the user switched levels, while
    having zoom in at max, so the nugget was visible.

 src/mining-activity/mining.py |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/src/mining-activity/mining.py b/src/mining-activity/mining.py
index 5748dd9..3be63dc 100644
--- a/src/mining-activity/mining.py
+++ b/src/mining-activity/mining.py
@@ -155,6 +155,7 @@ class Gcompris_mining:
     self.is_game_won = False
     self.nugget_count = 0
     self.need_new_nugget = False
+    self.nugget.hide()
 
     self.update_lorry()
     self.viewport.reset(level)