Zuul                           Git                            
 
                                                                               
 
       [X] Nova #1    SUCCESS             Nova        Keystone                 
 
        |             SUCCESS             * HEAD      * HEAD                   
 
        |--+        OOOOOOOOO..                                                
 
        |  |          SUCCESS                                                  
 
        |  |                                                                   
 
        | [X] Keystone #2   FAILURE                                            
 
        |                   SUCCESS                                            
 
        |                 OOOOOOO....                                          
 
        |                 OOOOOOOOO..                                          
 
        |                                                                      
 
       [X] Nova #3  OOOOOOO....                                                
 
        |           OOOOOOO....                                                
 
        |           OOOOO......                                                
 
        |           OOOOOO.....                                                
 
        |                                                                      
 
       [X] Nova #4  OOOO.......                                                
 
                    OOOO.......                                                
 
                    OO.........                                                
 
                    OOO........