dotcloud/docker — pull request #3346 by zimbatm (2013-12-25 16:27:20+00:00)
Title: Use plain HTTP transport for APT package delivery.

Package integrity is already verified by the GPG key so SSL is not necessary
to prevent MITM.

Some flavors of Ubuntu don't have the https transport available in APT which
makes the installation more difficult. It also impacts installation speed
since SSL requires at least one additional handshake.

The main Vagrantfile already uses http instead of https in the sources.list