Re: [PATCH 1/6] ci: deduplicate calls to `apt-get update`

> When installing dependencies we first check for the distribution that is
> in use and then we check for the specific job. In the first step we
> already install all dependencies required to build and test Git, whereas
> the second step installs a couple of additional dependencies that are
> only required to perform job-specific tasks.
>
> In both steps we use `apt-get update` to update our repository sources.
> This is unecessary though: all platforms that use Aptitude would have
> already executed this command in the distro-specific step anyway.
>