If the base_url is empty we should not pass it as an option, or pass it as a
NULL value so it is considered unset in url().

NOTE: Currently, the 'absolute' => TRUE setting is being ignored when the user
did not set a base_url, because an empty string is considered a valid
base_url in url().

Signed-off-by: Antonio Ospite <ospite@studenti.unina.it>

Index: nodewords_basic/nodewords_basic.module
===================================================================
RCS file: /cvs/drupal-contrib/contributions/modules/nodewords/nodewords_basic/nodewords_basic.module,v
retrieving revision 1.1.2.47
diff -u -r1.1.2.47 nodewords_basic.module
--- nodewords_basic/nodewords_basic.module	7 Dec 2009 22:35:02 -0000	1.1.2.47
+++ nodewords_basic/nodewords_basic.module	12 Dec 2009 21:04:28 -0000
@@ -242,7 +242,7 @@
   $base_url = rtrim(variable_get('nodewords_base_url', ''), '/');
   $options = array(
     'absolute' => TRUE,
-    'base_url' => $base_url,
+    'base_url' => empty($base_url) ? NULL : $base_url,
   );
 
   $tags['canonical'] = !empty($content['value']) ? check_url(url(drupal_get_path_alias($content['value']), $options)) : '';