Sugg: Improve for mock (caching)

[seth vidal]

> The network environment is incredibly fast where the buildsystems are.
> 
> The cache just adds a place for errors to happen if, for any reason,
> things get stale. 
> 
> -sv


I wanted to edit my remarks b/c they are a little more harsh than I
intended.

Sorry about that.

My concern is that we're fixing the wrong component. We should be in a
place where a chroot build is lightining fast.

If its not then we need to start checking out where the bottlenecks are.
If the ONLY thing that's making the chroot builds go slowly is the
network performance - meaning if we removed that problem everything
would be amazingly fast then we'd be better off not caching but having a
local mirror on the builder nodes.

But I don't think the network is the only bottleneck. I think there are
places in the installation mechanism where we can get some speedups.
Let's look at those instead?

-sv