[pitivi] render: Fix some handlers of widget changes

[Thibault Saunier <tsaunier src gnome org>]

commit 864449ccfaab2475d4dd6b8fa24408f32282f20d
Author: Alexandru Băluț <alexandru balut gmail com>
Date:   Sun Oct 18 19:37:27 2015 +0200

    render: Fix some handlers of widget changes
    
    Summary: set_combo_value always returns None.
    
    Reviewers: thiblahute
    
    Projects: #pitivi, #pitivi_0.95
    
    Reviewed By: thiblahute
    
    Differential Revision: https://phabricator.freedesktop.org/D351

 pitivi/render.py |    9 ++++++---
 1 files changed, 6 insertions(+), 3 deletions(-)
---
diff --git a/pitivi/render.py b/pitivi/render.py
index e855b96..7a169d5 100644
--- a/pitivi/render.py
+++ b/pitivi/render.py
@@ -497,13 +497,16 @@ class RenderDialog(Loggable):
             self.preferred_vencoder = value
 
     def sample_rate_setter(self, widget, value):
-        self.project.audiorate = set_combo_value(widget, value)
+        set_combo_value(widget, value)
+        self.project.audiorate = value
 
     def channels_setter(self, widget, value):
-        self.project.audiochannels = set_combo_value(widget, value)
+        set_combo_value(widget, value)
+        self.project.audiochannels = value
 
     def framerate_setter(self, widget, value):
-        self.project.videorate = set_combo_value(widget, value)
+        set_combo_value(widget, value)
+        self.project.videorate = value
 
     def bindHeight(self, mgr):
         mgr.bindWidget("height",