When a `tasks.py` module contains an explict Collection (named either `ns`
or `namespace`), the parent directory (used to find the project-specific
configuration file (e.g. `invoke.yaml`) is not passed in to the
Collection created from the factory method `Collection.from_module`.
This caused the file to not be found except when explicitly specified
with the -f flag. Compare to the similar Collection() invocation about
12 lines below this change.