[gnome-software] trivial: Prevent a warning when an AppStream entry defines X-XdgApp-Tags

[Richard Hughes <rhughes src gnome org>]

commit 6859882cf6b602fa740e715d95ed9de0bf9345e2
Author: Richard Hughes <richard hughsie com>
Date:   Fri Feb 19 13:48:37 2016 +0000

    trivial: Prevent a warning when an AppStream entry defines X-XdgApp-Tags

 src/plugins/gs-plugin-appstream.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/src/plugins/gs-plugin-appstream.c b/src/plugins/gs-plugin-appstream.c
index 3143769..ce8be19 100644
--- a/src/plugins/gs-plugin-appstream.c
+++ b/src/plugins/gs-plugin-appstream.c
@@ -569,7 +569,8 @@ gs_plugin_refine_item (GsPlugin *plugin, GsApp *app, AsApp *item, GError **error
        if (tmp != NULL) {
                if (g_str_has_prefix (tmp, "(Nightly) ")) {
                        tmp += 10;
-                       gs_app_set_metadata (app, "X-XdgApp-Tags", "Nightly");
+                       if (gs_app_get_metadata_item (app, "X-XdgApp-Tags") == NULL)
+                               gs_app_set_metadata (app, "X-XdgApp-Tags", "nightly");
                }
                gs_app_set_name (app, GS_APP_QUALITY_HIGHEST, tmp);
        }