[meld] Fix uninitialised tab when invoked with no args

[Kai Willadsen <kaiw src gnome org>]

commit 87c0df24981125e13b2bfa1f1d16c661a51ab25b
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Mon Dec 24 10:28:30 2012 +1000

    Fix uninitialised tab when invoked with no args

 meld/meldapp.py |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/meld/meldapp.py b/meld/meldapp.py
index 072b74d..fae1475 100644
--- a/meld/meldapp.py
+++ b/meld/meldapp.py
@@ -167,6 +167,8 @@ class MeldApp(gobject.GObject):
                 parser.error(_("Error reading saved comparison file"))
         elif args:
             tab = open_paths(args, options.auto_compare, options.auto_merge)
+        else:
+            tab = None
 
         if options.label and tab:
             tab.set_labels(options.label)