Phillip Smyth authored Nov 07, 2018 and Jürg Billeter committed Nov 12, 2018

_project.py: Added validate_nodes() helper function to prevent duplicate lists

element-path was being used before node validation resulting in uncaught errors

Element path not validated before use

See merge request !937

The Refactor now makes it possible to test for the forth coming multi
element workspace open commands and to test for failure.

This is to update the workspace CLI to as agreed on the mailing list
https://mail.gnome.org/archives/buildstream-list/2018-September/msg00046.html

This patch also introduces the default workspace directory.