Don't crawl through the same xdg_data_dirs twice

src/xdgmenumaker

@@ -192,9 +192,15 @@ def sortedcategories(applist):
 	return categories
 
 def desktopfilelist():
-	dirs = bd.xdg_data_dirs
+	dirs = []
+	# some directories are mentioned twice in bd.xdg_data_dirs, once
+	# with and once without a trailing /
+	for i in bd.xdg_data_dirs:
+		dirs.append(i.rstrip('/'))
+	dirs = set(dirs)
 	filelist = []
 	for d in dirs:
+		print d
 		xdgdir = d+'/applications'
 		if os.path.isdir(xdgdir):
 			for i in os.listdir(xdgdir):