In the tree described by checkout-1.delta, capital letters are
directories and greek letters are files.  There are no properties yet;
once we get file contents working, we'll add properties.


                                   A                       iota
          _______________________//|\
         /         ______________/ | \_____________
        mu        /                |               \
                 /                 |                \
                B                  C                 D
          _____/|\_____                _____________/|\
         /      |      \              /              | \
        /       |       \            /              /   \___
     lambda     |        F          /              /        \
                E                gamma            /          \
               / \                               /            |
              /   \                     ________/             |
          alpha   beta                 /                      H
                                      /               _______/|\______
                                     /               /        |       \
                                    G               /         |        \
                           ________/|\_______     chi        psi      omega
                          /         |        \
                         /          |         \
                        /           |          \
                       pi          rho         tau