[gnome-shell] extensionSystem: Don't load extensions multiple times

[Ray Strode <halfline src gnome org>]

commit 6df48b68fadf38d171b318ebb000548d6371672c
Author: Ray Strode <rstrode redhat com>
Date:   Mon Oct 18 11:41:39 2010 -0400

    extensionSystem: Don't load extensions multiple times
    
    Right now if XDG_DATA_DIRS is set to have duplicate entries,
    then the extension system will try to load all extensions
    more than once.
    
    This commit prevents an extension from getting repeatedly
    loaded by checking if its uuid is already registered.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=632477

 js/ui/extensionSystem.js |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)
---
diff --git a/js/ui/extensionSystem.js b/js/ui/extensionSystem.js
index 944e2e5..5315d90 100644
--- a/js/ui/extensionSystem.js
+++ b/js/ui/extensionSystem.js
@@ -51,6 +51,12 @@ function loadExtension(dir, enabled, type) {
             return;
         }
     }
+
+    if (extensions[meta.uuid] != undefined) {
+        global.logError(baseErrorString + "extension already loaded");
+        return;
+    }
+
     // Encourage people to add this
     if (!meta['url']) {
         global.log(baseErrorString + 'Warning: Missing "url" property in metadata.json');