update_metadata re-config on every boot comments and tests not quite right
The comment in update_metadata() that explains how a datasource should
enable network reconfig on every boot presumes that
EventType.BOOT_NEW_INSTANCE is a subset of EventType.BOOT. That's not
the case, and as such a datasource that needs to configure networking
when it is a new instance and every boot needs to include both event
types.
To make the situation above easier to debug, update_metadata() now
logs when it returns false.
To make it so that datasources do not need to test before appending to
the update_events['network'], it is changed from a list to a set.
test_update_metadata_only_acts_on_supported_update_events is updated
to allow datasources to support EventType.BOOT.
tests: Collect build_info from system if available.
This adds a script to always get the /etc/cloud/build.info file
if it exists, and a hook when preparing the image to log the information
if it is available.
INFO - setting up ubuntu-cosmic (build_name=server serial=20180718)
pylint: Fix pylint warnings reported in pylint 2.0.0.
Pylint 2.0.0 was recently released and complains more about
logging-not-lazy than it used to. I've fixed those warnings, here.
The changes in rh_subscription are more extensive. pylint may be
complaining incorrectly there, but the tests were not correctly un-doing
all of their mock/patching. This cleans those up and makes pylint happy.
