wxGUI: minor fix in uninstall-extension dialog (windows-related)

       (merge https://trac.osgeo.org/grass/changeset/50008 from devbr6)


git-svn-id: https://svn.osgeo.org/grass/grass/trunk@50009 15284696-431f-4ddb-bdfa-cd5b030d7da7

gui/wxpython/modules/extensions.py

@@ -486,7 +486,8 @@ class CheckListExtension(wx.ListCtrl, listmix.ListCtrlAutoWidthMixin, listmix.Ch
         for ext in RunCommand('g.extension',
                               quiet = True, parent = self, read = True,
                               flags = 'a').splitlines():
-            self.InsertStringItem(sys.maxint, ext)
+            if ext:
+                self.InsertStringItem(sys.maxint, ext)
 
     def GetExtensions(self):
         """!Get extensions to be un-installed