Updated openstack/openstack
Project: openstack/glance_store  16295ae977ef70e23ec02bac5a2340a7dd22d7c5

Use statvfs instead of df to get available space

We should use Python's standard library if possible.

Change-Id: I923fe11aa7ffddef6f59970f889d3e7e58f4af68
Closes-Bug: 1386060