[pitivi] proxy: Never create proxies for images

[Thibault Saunier <tsaunier src gnome org>]

commit 10372dfbee85bcb201623ce9aa518fac79ae5b39
Author: Thibault Saunier <tsaunier gnome org>
Date:   Fri Jan 22 23:28:29 2016 +0100

    proxy: Never create proxies for images
    
    Fixes T3539

 pitivi/utils/proxy.py |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/pitivi/utils/proxy.py b/pitivi/utils/proxy.py
index 074c437..06e02ac 100644
--- a/pitivi/utils/proxy.py
+++ b/pitivi/utils/proxy.py
@@ -211,6 +211,9 @@ class ProxyManager(GObject.Object, Loggable):
             self.info("No proxying supported")
             return False
 
+        if asset.is_image():
+            return False
+
         if force_proxying:
             self.info("Forcing proxy creation")
             return True