[pitivi] Fix an exception tracking edges of a newly dragged clip.

[Edward Hervey <edwardrv src gnome org>]

commit 0d0dd3a060d5242fc1b7bc2049289d23ed33fbfa
Author: Alessandro Decina <alessandro d gmail com>
Date:   Mon Jul 13 15:59:22 2009 +0200

    Fix an exception tracking edges of a newly dragged clip.

 pitivi/timeline/timeline.py |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/pitivi/timeline/timeline.py b/pitivi/timeline/timeline.py
index a90b826..eae3864 100644
--- a/pitivi/timeline/timeline.py
+++ b/pitivi/timeline/timeline.py
@@ -723,6 +723,8 @@ class TimelineEdges(object):
         except KeyError:
             raise TimelineError()
 
+        self.changed_objects.pop(track_object, None)
+
         start = track_object.start
         end = track_object.start + track_object.duration
         self.removeStartEnd(start, end)