bcb73dd2ac
In our onging quest to find a stable upstream source, switch this to the facebook mirror which seems to have been working well enough for centos. While we're here, reduce the frequency a bit as there's no need to sync every two hours; it's a bit unfriendly to the remote end. Change-Id: I50f38b58b3f0c0557fb1e2e0667a17a4f1d1dec6