[simple-scan/gnome-3-28] Use GLib.List.deep_copy() to fix type-argument mismatch

[Robert Ancell <rancell src gnome org>]

commit 9807755bcec0a8b430d572533bcfd60479b11f45
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Mon Nov 5 15:00:25 2018 +0100

    Use GLib.List.deep_copy() to fix type-argument mismatch

 src/simple-scan.vala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/simple-scan.vala b/src/simple-scan.vala
index d30aa45..0c263f0 100644
--- a/src/simple-scan.vala
+++ b/src/simple-scan.vala
@@ -105,7 +105,7 @@ public class SimpleScan : Gtk.Application
 
     private void update_scan_devices_cb (Scanner scanner, List<ScanDevice> devices)
     {
-        var devices_copy = devices.copy ();
+        var devices_copy = devices.copy_deep ((CopyFunc) Object.ref);
 
         /* If the default device is not detected add it to the list */
         if (default_device != null)