[pitivi] flatpak: Fix is_installed for subpackages

[Thibault Saunier <tsaunier src gnome org>]

commit b114da72c08f2afbd85a953ec86887bd8fc6634f
Author: Alexandru Băluț <alexandru balut gmail com>
Date:   Wed Jul 18 21:44:09 2018 +0200

    flatpak: Fix is_installed for subpackages
    
    flatpak info returns an error if there are multiple versions of the
    subpackage installed, requiring one of them to be specified.

 build/flatpak/pitivi-flatpak | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/build/flatpak/pitivi-flatpak b/build/flatpak/pitivi-flatpak
index 78ce0f79..6da07fcc 100755
--- a/build/flatpak/pitivi-flatpak
+++ b/build/flatpak/pitivi-flatpak
@@ -328,10 +328,10 @@ class FlatpakPackage(FlatpakObject):
                     return True
         else:
             try:
-                self.flatpak("info", self.name)
+                self.flatpak("info", self.name, self.branch)
                 return True
             except subprocess.CalledProcessError:
-                return False
+                pass
 
         return False