Bug#778701: Wrong disk usage displayed

[jnqnfe]

Package: gnome-system-monitor
Version: 3.14.1-1

Gnome system monitor is reporting inaccurate disk usage information.

Example (1TB HDD):
total: 984.4GB
available: 46.7 GB
used: 887.7 GB
95% full

887.7 + 46.7 = 934.4, not 984.4

The used amount is correct, as is the total (I believe), but the amount
available is significantly off and so thus is the percentage.

gnome-disk-utility however reports the correct usage:
Size: 1.0 TB - 97 GB free )90.3% full).