The `update-rc.d` command in the `init-system-helpers` package is
required by the `linux-util` postinst script, but `init-system-helpers`
doesn't seem to be installed by default in 11/bullseye.
The suite name for the updates repository has also changed in
11/bullseye.
Tweak the tests so that they use default-mysql-server
on newer dists as it replaced the mysql-server package.
Also add explicit import of the buster signing key
as the Travis agent doesn't have it available.
Thanks to Filippo Giunchedi (@filippog) for the initial
work on this.
It's an essential package designed for exactly this.
It's pretty small, so not a huge cost to putting it back in.
The problem is pervasive enough, and it's unlikely that
users will know how to fix it, that it's worth us solving
it in the base image.
sysv-rc and util-linux are used in the postinst scripts
of some packages, and so those packages won't install
if they aren't available.
sysv-rc contains update-rc.d, so any package that installs
a service would fail to install. Those packages are common
to install in to containers.
util-linux contains the getopt command which some scripts
expect to find.
John Kristensen