[pitivi] track: fix runtime warning

[Jean-François Fortin Tam <jfft src gnome org>]

commit 61dbfb0805e156e2bd39157c304a3561d3b287c1
Author: Lubosz Sarnecki <lubosz gmail com>
Date:   Tue Apr 9 22:21:31 2013 +0200

    track: fix runtime warning
    
     RuntimeWarning: Expecting to marshal a borrowed reference for <Pixbuf
    object at 0x44f7a00 (GdkPixbuf at 0x4880000)>, but nothing in Python is
    holding a reference to this object. See:
    https://bugzilla.gnome.org/show_bug.cgi?id=687522

 pitivi/timeline/track.py |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/pitivi/timeline/track.py b/pitivi/timeline/track.py
index 1d3f272..f3011b3 100644
--- a/pitivi/timeline/track.py
+++ b/pitivi/timeline/track.py
@@ -284,10 +284,11 @@ class TrimHandle(View, GooCanvas.CanvasImage, Loggable, Zoomable):
     height = property(getHeight, setHeight)
 
     def _scalePixbuf(self):
-        self.props.pixbuf = self.current_pixbuf.scale_simple(
+        new_pixbuf = self.current_pixbuf.scale_simple(
             self.current_pixbuf.get_width(),
             self.height,
             GdkPixbuf.InterpType.BILINEAR)
+        self.props.pixbuf = new_pixbuf
 
 
 class StartHandle(TrimHandle):