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:worker.py
             product   st:../pkgs_a/
             product   step:./worker.py

st:../pkgs_a/
             creator   step:./plan.py
             product   file:../pkgs_a/helper.py

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

step:./worker.py
               state = SUCCEEDED
                need = DEFAULT
           using_env = STEPUP_PATH_FILTER [dynamic]
             creator   step:./plan.py
              source   file:../pkgs_a/helper.py [dynamic]
              source   file:worker.py

file:../pkgs_a/helper.py
               state = CONFIRMED
             creator   st:../pkgs_a/
                sink   step:./worker.py
