Rename folder dialog does not always automatically update URL name

The 'rename folder' dialog does not automatically update the URL name of a folder when the name of a folder is changed. Only after clicking 'reset', the URL name is automatically updated again while changing the folder name. This only happens for first-level subfolders. For example, with the path /news/2009/03, renaming the folders 'news' and '03' works fine, but renaming '2009' does not update the URL name automatically.

Steps to reproduce:
1. in the CMS, go to the documents
2. create a new folder "foo" inside a root folder
3. rename folder "foo" to "bar"

Expected behavior: the URL name of "foo" is automatically changed to "bar"
Actual behavior: the URL name of "foo" remains "foo". Clicking "OK" then shows the error message "Cannot rename document to same name."