I was trying to find an example for this, do you have one in mind?
````
>>> print urljoin('http://test//', '/at/sfé/')
http://test/at/sfé/
````
The problem I saw was more when the base_url has two trailing slashes:
````
>>> print urljoin('http://test//', 'at/sfé/')
http://test//at/sfé/
````