Qinusty authored Jul 23, 2018 and Tristan Van Berkom committed Aug 06, 2018

This address issue #491.

When attempting to run buildstream with a configuration specifying
a cache quota larger than your available disk space, buildstream
will alert the user and exit.

Note:
This takes into consideration your current cache usage and
therefore restricts the overall size of your artifact cache folder.

Backport cache quota restriction to 1.2

See merge request !607