Don't include archive diectories that are missing an image.zip when calculating previous image.
This change allows for a previous archive directory to be devoid of an image.zip
without throwing an exception when generating delta payloads. Sometimes we might
be missing an image.zip directory if the state of the last build was bad i.e. it
was aborted midstream -- archive directory is created but image.zip doesn't finish
getting generated.
I've also updated a lot of the logging/docstring to make clear what's happening
in image_extractor.
BUG=chromium-os:32122
TEST=Unittests + pylint + running with full_suite w/ and w/out image.zip in latest.
Change-Id: Ie1719e30a7c96283e6d8384719d000fb86c83984
Reviewed-on: https://gerrit.chromium.org/gerrit/29426
Reviewed-by: Chris Sosa <sosa@chromium.org>
Tested-by: Chris Sosa <sosa@chromium.org>
3 files changed
