Prevent crash on launch during a backup.osp recovery

Author: jonoomph

src/windows/preview_thread.py

@@ -1,26 +1,26 @@
-""" 
+"""
  @file
  @brief This file contains the preview thread, used for displaying previews of the timeline
  @author Jonathan Thomas <[email protected]>
- 
+
  @section LICENSE
- 
+
  Copyright (c) 2008-2018 OpenShot Studios, LLC
  (http://www.openshotstudios.com). This file is part of
  OpenShot Video Editor (http://www.openshot.org), an open-source project
  dedicated to delivering high quality video editing and animation solutions
  to the world.
- 
+
  OpenShot Video Editor is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.
- 
+
  OpenShot Video Editor is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
- 
+
  You should have received a copy of the GNU General Public License
  along with OpenShot Library.  If not, see <http://www.gnu.org/licenses/>.
  """
@@ -334,5 +334,5 @@ def Speed(self, new_speed):
         """ Set the speed of the video player """
 
         # Set speed
-        if self.parent.initialized:
+        if self.parent.initialized and self.player.Speed() != new_speed:
             self.player.Speed(new_speed)