appengine/aetest: make aetest work with "vm: true" apps
appengine/aetest: make aetest work with "vm: true" apps

Change-Id: Iec495b87f3fa2ec4aae10853f9fd350d27c26121

mzimmerman/appengine,golang/appengine,mzimmerman/appengine,fuchsia-mirror/third_party-github.com-golang-appengine,fuchsia-mirror/third_party-github.com-golang-appengine,mzimmerman/appengine,golang/appengine