root:
             product   file:plan.py
             product   step:./plan.py

file:plan.py
               state = CONFIRMED
             creator   root:
                sink   step:./plan.py

step:./plan.py
               state = SUCCEEDED
                need = PLAN
           using_env = STEPUP_PATH_FILTER [dynamic]
             creator   root:
              source   file:plan.py
             product   file:original.txt
             product   step:cp between.txt another.txt
             product   step:cp original.txt between.txt

file:another.txt
               state = BUILT
             creator   step:cp between.txt another.txt
              source   step:cp between.txt another.txt

file:original.txt
               state = CONFIRMED
             creator   step:./plan.py
                sink   step:cp original.txt between.txt

step:cp between.txt another.txt
               state = SUCCEEDED
                need = DEFAULT
             creator   step:./plan.py
              source   file:between.txt
             product   file:another.txt
                sink   file:another.txt

file:between.txt
               state = BUILT
             creator   step:cp original.txt between.txt
              source   step:cp original.txt between.txt
                sink   step:cp between.txt another.txt

step:cp original.txt between.txt
               state = SUCCEEDED
                need = DEFAULT
             creator   step:./plan.py
              source   file:original.txt
             product   file:between.txt
                sink   file:between.txt
