[gtk/gtk-3-24] action muxer: Be safe against reinsertion

[Matthias Clasen <matthiasc src gnome org>]

commit e873c98e25340178aaeb5f5197b5cc386428a4e1
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Jun 23 22:55:19 2019 +0000

    action muxer: Be safe against reinsertion
    
    Be prepared for the eventuality that somebody
    might reinsert the same action group without
    holding any extra references on it.
    
    This was observed as causing crashes in
    gnome-builder.

 gtk/gtkactionmuxer.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
---
diff --git a/gtk/gtkactionmuxer.c b/gtk/gtkactionmuxer.c
index ee97cd294f..d6c3d26161 100644
--- a/gtk/gtkactionmuxer.c
+++ b/gtk/gtkactionmuxer.c
@@ -683,12 +683,14 @@ gtk_action_muxer_insert (GtkActionMuxer *muxer,
   Group *group;
   gint i;
 
+  g_object_ref (action_group);
+
   /* TODO: diff instead of ripout and replace */
   gtk_action_muxer_remove (muxer, prefix);
 
   group = g_slice_new (Group);
   group->muxer = muxer;
-  group->group = g_object_ref (action_group);
+  group->group = action_group;
   group->prefix = g_strdup (prefix);
 
   g_hash_table_insert (muxer->groups, group->prefix, group);