[gnome-flashback/gnome-3-20] end-session-dialog: ignore invalid inhibitor

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 69e900a7b27bdbed31e3658f007214165b10221b
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Fri Nov 18 17:14:11 2016 +0200

    end-session-dialog: ignore invalid inhibitor
    
    https://bugzilla.gnome.org/show_bug.cgi?id=771759

 .../libend-session-dialog/gf-inhibit-dialog.c      |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/gnome-flashback/libend-session-dialog/gf-inhibit-dialog.c 
b/gnome-flashback/libend-session-dialog/gf-inhibit-dialog.c
index 50b2b36..b5f8fa2 100644
--- a/gnome-flashback/libend-session-dialog/gf-inhibit-dialog.c
+++ b/gnome-flashback/libend-session-dialog/gf-inhibit-dialog.c
@@ -295,6 +295,9 @@ add_inhibitor (GfInhibitDialog *dialog,
   name = NULL;
   pixbuf = NULL;
 
+  if (app_id == NULL)
+    return;
+
   if (!IS_STRING_EMPTY (app_id))
     {
       if (!g_str_has_suffix (app_id, ".desktop"))