[dconf-editor] Do not warn on empty string.

[Arnaud Bonatti <arnaudb src gnome org>]

commit e169676347c76cab0a717725ca5a5e005565ee13
Author: Arnaud Bonatti <arnaud bonatti gmail com>
Date:   Mon Feb 26 18:07:29 2018 +0100

    Do not warn on empty string.

 editor/dconf-window.vala |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/editor/dconf-window.vala b/editor/dconf-window.vala
index 4e70a2a..287f90b 100644
--- a/editor/dconf-window.vala
+++ b/editor/dconf-window.vala
@@ -152,7 +152,8 @@ class DConfWindow : ApplicationWindow
         }
         else
         {
-            warning ("Unknown schema %s.".printf ((!) schema));
+            if ((!) schema != "")
+                warning (_("Unknown schema “%s”.").printf ((!) schema));
             if (settings.get_boolean ("restore-view"))
                 first_path = settings.get_string ("saved-view");
         }