(PUP-3277) Add dir env to file/source_attribute test

This commit modifies the file/source_attribute test to use
directory environments.
(PUP-3277) Make whitespace consistent in file/source_attribute test

Only indent in blocks; step() calls without blocks.
Merge branch 'pup-3277-file-source-attribute'

* pup-3277-file-source-attribute:
  (PUP-3277) Make whitespace consistent in file/source_attribute test
  (PUP-3277) Add dir env to file/source_attribute test