[libdazzle] shortcuts: only add command once

[Christian Hergert <chergert src gnome org>]

commit dce075b0df6b6b31e46c666ceee7b1ec8fb80103
Author: Christian Hergert <chergert redhat com>
Date:   Wed Jul 19 23:35:06 2017 -0700

    shortcuts: only add command once
    
    We create these controllers at runtime and that means that we
    could add the commands multiple times if we're not careful.

 src/shortcuts/dzl-shortcut-controller.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/src/shortcuts/dzl-shortcut-controller.c b/src/shortcuts/dzl-shortcut-controller.c
index 8b2f554..1d7b06f 100644
--- a/src/shortcuts/dzl-shortcut-controller.c
+++ b/src/shortcuts/dzl-shortcut-controller.c
@@ -1101,7 +1101,8 @@ dzl_shortcut_controller_add_command (DzlShortcutController   *self,
 
           /* Hook things up into the default context */
           context = _dzl_shortcut_theme_find_default_context_with_phase (theme, priv->widget, phase);
-          dzl_shortcut_context_add_command (context, default_accel, command_id);
+          if (!_dzl_shortcut_context_contains (context, chord))
+            dzl_shortcut_context_add_command (context, default_accel, command_id);
         }
       else
         g_warning ("\"%s\" is not a valid accelerator chord", default_accel);