change behavior to fit the doc string :

  base -- a boolean or a string. If it is a string, then use
          that string as a base

before, if it was a string it was never used because the expression 
"if str("something"):" is always True


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@38811 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/CMFCategory/Category.py

@@ -365,7 +365,9 @@ class Category(Folder):
       """
       if not base:
         base = '' # Make sure we get a meaningful base
-      if base:
+      elif isinstance(base, str):
+        base = base + '/'
+      elif base:
         base = self.getBaseCategoryId() + '/' # Make sure we get a meaningful base
       url_list = []
       for value in self.getCategoryChildValueList(recursive=recursive,