Comment 18 for bug 1571764

I believe that the root cause of this bug was actually bug 1577712 that we fixed in June (Yakkety) and July (Xenial, 16.04), so am marking this bug as a duplicate of that one. See bug 1577712 for details.

For others subscribed to this bug, or otherwise believe they're affected by this issue: I see many comments above that I think are clearly due to unrelated issues, so this bug is probably not the one you want.