tests/acceptance: Add Test.fetch_asset(cancel_on_missing=True)

Invert the default of avocado.Test.fetch_asset 'cancel_on_missing'
keyword: accept missing artefacts by default. If a test is certain
an artifact can't be missing, it will set cancel_on_missing=False.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20200908202352.298506-3-philmd@redhat.com>
Message-Id: <20200909112742.25730-10-alex.bennee@linaro.org>
1 file changed