Cloud config modules are not skipped based on distro support

[Chad Smith]

cloudinit.stages emits logs messages like the following when the cloudconfig module's distro attribute doesn't match the running disribution

When a cloudinit.config.cc*py module distros attribute doesn't match the discovered Distribution.name, cloudinit.stages emits a log message about skipping the module in the following form:

2017-09-07 06:03:25,838 - stages.py[INFO]: Skipping modules ['runcmd'] because they are not verified on distro 'ubuntu'. To run anyway, add them to 'unverified_modules' in config.

But, it doesn't actually skip running the module, we can see in the logging that follows:
Running module runcmd (<module 'cloudinit.config.cc_runcmd' from '/usr/lib/python3/dist-packages/cloudinit/config/cc_runcmd.py'>) with frequency once-per-instance.

cloudinit.stages should honor a skipped module and avoid running its handler.

[Chad Smith (chad.smith)]

Might also look into unverified_modules behavior, it looks like it is ineffective as well. Just a log message and no further change in behavior made by run_section.

[Scott Moser (smoser)]

This bug is believed to be fixed in cloud-init in 17.1. If this is still a problem for you, please make a comment and set the state back to New

Thank you.

[James Falcon (falcojr)]

Tracked in Github Issues as https://github.com/canonical/cloud-init/issues/2995