def test_content_add_collision_sha256(self):                        
    cont1 = self.cont                                               
                                                                    
    # create (corrupted) content with same sha256 but != sha1{,_git}
    cont1b = cont1.copy()                                           
    sha1_array = bytearray(cont1b['sha1'])                          
    sha1_array[0] += 1                                              
    cont1b['sha1'] = bytes(sha1_array)                              
    sha1git_array = bytearray(cont1b['sha1_git'])                   
    sha1git_array[0] += 1                                           
    cont1b['sha1_git'] = bytes(sha1git_array)                       
                                                                    
    self.storage.content_add([cont1, cont1b])