Vagrant fails to set permissions on SSH public keys in created VMs

Vagrant 1.8.5+dfsg-2 on Ubuntu 16.10.

When creating a new vagrant VM, vagrant gets stuck after the following:

==> default: Waiting for SSH to become available...
    default:
    default: Vagrant insecure key detected. Vagrant will automatically replace
    default: this with a newly generated keypair for better security.
    default:
    default: Inserting generated public key within guest...
    default: Removing insecure key from the guest if it's present...
    default: Key inserted! Disconnecting and reconnecting using new SSH key...

This is because it fails to set the proper permissions on the SSH key it inserts (which causes subsequent logins to fail).

This has already been fixed upstream: https://github.com/mitchellh/vagrant/issues/7610

ProblemType: Bug
DistroRelease: Ubuntu 16.10
Package: vagrant 1.8.5+dfsg-2
ProcVersionSignature: Ubuntu 4.8.0-34.36-generic 4.8.11
Uname: Linux 4.8.0-34-generic x86_64
ApportVersion: 2.20.3-0ubuntu8.2
Architecture: amd64
CurrentDesktop: i3
Date: Fri Mar 31 15:08:23 2017
InstallationDate: Installed on 2016-04-18 (346 days ago)
InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
PackageArchitecture: all
SourcePackage: vagrant
UpgradeStatus: Upgraded to yakkety on 2017-01-13 (76 days ago)