With this fix in place the script mitm-serve-app-dev.sh works
as advertised. It proxies the https prod server and even allows
login. It is fairly slow though compared to run-server.sh, so
it cannot fully replace it at this point.
Note that there is also a WIP Change I0ff7e314a for getting us
from mitmproxy 2.0.2 to 4.0.4.
Change-Id: Id79510228d6e701f724cc947146768fabae58457