Don't do any caching logic if we are only serving payloads.

Currently, if we are only supposed to be serving images, the devserver
-at startup- might still try to clean its cache. This is unintended and
incorrect. If we are only supposed to be serving payloads, we shouldn't
have any additional side-effects.

BUG=chromium-os:34768
TEST=Ran w/ w/out archive_dir also ran unittests + pylint + --clear_cache w |
w/out data. A canary with vmtests and a paladin.

Change-Id: I7f97f9748f7eecac9da443b5881adac443f00fcd
Reviewed-on: https://gerrit.chromium.org/gerrit/39510
Commit-Ready: Chris Sosa <sosa@chromium.org>
Reviewed-by: Chris Sosa <sosa@chromium.org>
Tested-by: Chris Sosa <sosa@chromium.org>
1 file changed