Add workaround for stdio prefix being incorrectly stored in expanded form as 'None' with no master.
Add workaround for stdio prefix being incorrectly stored in expanded form
as 'None' with no master.

BUG=chromium:604990

Review URL: https://codereview.chromium.org/1902983003

catapult-project/catapult-csm,catapult-project/catapult,catapult-project/catapult,sahiljain/catapult,benschmaus/catapult,sahiljain/catapult,benschmaus/catapult,benschmaus/catapult,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult-csm,benschmaus/catapult,catapult-project/catapult-csm,benschmaus/catapult,benschmaus/catapult,sahiljain/catapult,catapult-project/catapult-csm,catapult-project/catapult,catapult-project/catapult-csm,catapult-project/catapult-csm,sahiljain/catapult,catapult-project/catapult-csm,catapult-project/catapult,benschmaus/catapult,sahiljain/catapult,catapult-project/catapult,sahiljain/catapult