[pitivi] undo: Disconnect from the signals correctly.

[Thibault Saunier <tsaunier src gnome org>]

commit e82efbb5d54430a852de270c5ae7f104866ac2ef
Author: Mathieu Duponchelle <mathieu duponchelle opencreed com>
Date:   Thu May 1 13:22:13 2014 +0200

    undo: Disconnect from the signals correctly.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=739251

 pitivi/undo/timeline.py |   12 ++++++------
 1 files changed, 6 insertions(+), 6 deletions(-)
---
diff --git a/pitivi/undo/timeline.py b/pitivi/undo/timeline.py
index 9bb4ffc..6bb5a12 100644
--- a/pitivi/undo/timeline.py
+++ b/pitivi/undo/timeline.py
@@ -272,12 +272,12 @@ class TimelineLogObserver(object):
         timeline.connect("layer-removed", self._layerRemovedCb)
 
     def _disconnectFromTimeline(self, timeline):
-        try:
-            timeline.disconnect_by_func(self._clipAddedCb)
-            timeline.disconnect_by_func(self._clipRemovedCb)
-        except TypeError:
-            # Was not connected to any layer yet
-            pass
+        for layer in timeline.get_layers():
+            layer.disconnect_by_func(self._clipAddedCb)
+            layer.disconnect_by_func(self._clipRemovedCb)
+
+        timeline.disconnect_by_func(self._layerAddedCb)
+        timeline.disconnect_by_func(self._layerRemovedCb)
 
     def _connectToClip(self, clip):
         tracker = ClipPropertyChangeTracker()