[pitivi] timeline: Make sure to disconnect _positionCb

[Thibault Saunier <tsaunier src gnome org>]

commit aafa55bc1b2bed9978b40a3bb3549d8cdd61ff27
Author: Alexandru Băluț <alexandru balut gmail com>
Date:   Thu Apr 27 01:09:00 2017 +0200

    timeline: Make sure to disconnect _positionCb
    
    What's connected should be disconnected at some point.
    
    Reviewed-by: Thibault Saunier <tsaunier gnome org>
    Differential Revision: https://phabricator.freedesktop.org/D1733

 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 d353c42..7d62fa4 100644
--- a/pitivi/timeline/timeline.py
+++ b/pitivi/timeline/timeline.py
@@ -452,6 +452,8 @@ class Timeline(Gtk.EventBox, Zoomable, Loggable):
             self.ges_timeline.ui = None
             self.ges_timeline = None
 
+        if self._project:
+            self._project.pipeline.disconnect_by_func(self._positionCb)
         self._project = project
         if self._project:
             self._project.pipeline.connect('position', self._positionCb)