Installing aegir tries to use non-fpm php packages even if the
fpm package is already installed. Try to circumvent this behaviour
by passing the extra packages directly to the apt-get command as
suggested in the documentation.
@see https://aegir.readthedocs.io/en/3.x/install/#6-optional-install-with-nginx
Puppet doesn't support variable reassignment, so using concat() from
the puppetlabs/stdlib seems to be easier than making up a series of
arbitrary variable names.
Puppet removed the "+=" and "-=" operators. Replaced with $a = $a +
$b, which requires Puppet 4.x. If compatibility with 3.x is desired,
the code needs to be changed to use an external function, like concat().
Kienan Stewart