[pitivi/1.0] build: Use --if-not-exists when adding a remote

[Alexandru Băluț <alexbalut src gnome org>]

commit 23448240bd92ed580f107a4bb7f85b5865a12c62
Author: Damanpreet Singh <daman 4880 gmail com>
Date:   Sun Feb 18 14:45:31 2018 +0530

    build: Use --if-not-exists when adding a remote

 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 2031ab3..b3df0aa 100755
--- a/build/flatpak/pitivi-flatpak
+++ b/build/flatpak/pitivi-flatpak
@@ -239,7 +239,7 @@ class FlatpakRepos(FlatpakObject):
             same_name.url = repo.url
             return same_name
 
-        self.flatpak("remote-add", repo.name, "--from",
+        self.flatpak("remote-add", "--if-not-exists", repo.name, "--from",
                      repo.repo_file.name,
                      comment="Adding repo %s" % repo.name)
         repo.repos = self