Android hands the intent that started the task back to onCreate every
time the activity is recreated, so a single reminder or widget event tap
re-opened that event on every later launch — an error screen once the
event had been deleted.
Hold back the event channels when the launch is a recreation or a resume
from recents. The other channels keep re-reading the intent: an .ics
import or a prefilled create form has no saved state of its own, so that
replay is what carries them through a rotation.