Let's keep this repository as accessible to contributors as possible!

This way, we can fully run the mirror script in dry-run mode.

They are thin wrappers over `system`, but two main points:

 * They log the (unescaped) command.
 * `run` will auto-die.

This removes the need to pepper `== 0 or die` in the script.

Passing a list of parameters to `system` automatically gives us peace of
mind with regards to shell escaping. This is because it will not rely on
a shell invocation to run the given parameters, but directly exec to it.

The left-over shell invocations all use redirection.