[pitivi] build: Initialize variable before the try block

[Alexandru Băluț <alexbalut src gnome org>]

commit 28d187ea12a6e8837037abcf8cef4740cd7ece8d
Author: Alexandru Băluț <alexandru balut gmail com>
Date:   Tue Oct 25 15:41:09 2016 +0200

    build: Initialize variable before the try block
    
    Reviewed-by: Thibault Saunier <tsaunier gnome org>
    Differential Revision: https://phabricator.freedesktop.org/D1467

 build/flatpak/pitivi-flatpak |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/build/flatpak/pitivi-flatpak b/build/flatpak/pitivi-flatpak
index 3d19933..57d8c91 100755
--- a/build/flatpak/pitivi-flatpak
+++ b/build/flatpak/pitivi-flatpak
@@ -349,8 +349,8 @@ class PitiviFlatpak:  # pylint: disable=too-many-instance-attributes
 
         self.build_name = self.name
         if os.path.exists(os.path.join(self.topdir, ".git")):
+            devnull = open(os.devnull)
             try:
-                devnull = open(os.devnull)
                 self.build_name = self.name + "." + subprocess.check_output(
                     "git rev-parse --abbrev-ref HEAD".split(
                         " "), stderr=devnull,