[pitivi] timeline.Track: Fill in GnlSource before putting it in a GnlComposition.

[Edward Hervey <edwardrv src gnome org>]

commit c22bf55bc420b6f39637381fa84e9aed5c59c81d
Author: Edward Hervey <bilboed bilboed com>
Date:   Thu Jul 16 16:43:26 2009 +0200

    timeline.Track: Fill in GnlSource before putting it in a GnlComposition.
    
    This avoids a race-condition where the GnlSource wouldn't be ready before the
    moment GnlComposition tries to use it.

 pitivi/timeline/track.py |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)
---
diff --git a/pitivi/timeline/track.py b/pitivi/timeline/track.py
index 526a2f1..d0035ad 100644
--- a/pitivi/timeline/track.py
+++ b/pitivi/timeline/track.py
@@ -699,16 +699,18 @@ class Track(Signallable):
         if track_object.track is not None:
             raise TrackError()
 
-        try:
-            self.composition.add(track_object.gnl_object)
-        except gst.AddError:
+        if track_object.gnl_object in list(self.composition):
             raise TrackError()
-
         track_object.makeBin()
 
         track_object.track = weakref.proxy(self)
         self.track_objects.append(track_object)
 
+        try:
+            self.composition.add(track_object.gnl_object)
+        except gst.AddError:
+            raise TrackError()
+
         self._connectToTrackObjectSignals(track_object)
 
         self._updateMaxPriority()