Comment 0 for bug 2039621

Upstream commit 015543d304[1] introduced the ability to install missing dependencies (software-properties-common or gnupg) when running on minimal images with custom cloud-config that contains APT configuration that requires interaction with those tools.

The commit also introduced a default case on first boot where, regardless of whether apt configuration is present, apt update will be called.
This adds an initial boot delay of around 2 seconds and apt update should be avoided unless packages are going to be installed or `package_update: true` is provided in cloud-config user-data.

[1] https://github.com/canonical/cloud-init/commit/015543d304

The resolution here is to avoid calling the method cloud.distro.install_packages(missing_packages) when no packages need to be installed because the side-effect of this install_packages call is a run of 'apt update'.