human
Solve the following python programming problem given the following code:
def test_relative_local_find_links(self, finder, monkeypatch) : 
    '
        Test a relative find_links path is joined with the req file directory
        ' 
    req_file = os.path.normcase (os.path.abspath (os.path.normpath ('/path/req_file.txt'))) 
    nested_link = os.path.normcase (os.path.abspath (os.path.normpath ('/path/rel_path'))) 
    exists_ = os.path.exists 
    def exists(path) : 
        if (path == nested_link) : 
            return True 
else : 
            exists_ (path) 
monkeypatch.setattr (os.path, 'exists', self) 
    list (process_line ('--find-links=rel_path', req_file, 1, finder = finder)) 
    assert (finder.find_links == [nested_link]) 

    
    

    Fix the buggy line: monkeypatch.setattr (os.path, 'exists', self)
assistant
#Here is Python code to fix the buggy line: monkeypatch.

monkeypatch.setattr (os.path, 'exists', exists)