Workaround for the Thunderbird error "MODIFICATION_FAILED" after updating the calendar.

Mark A. Forkner (former Chief Technical Pilot for Boeing) provided the Federal Aviation Administration’s Aircraft Evaluation Group with materially false, inaccurate, and incomplete information about a new part of the flight controls for the Boeing 737 MAX called the Maneuvering Characteristics Augmentation System (MCAS).
“In an attempt to save Boeing money, Forkner allegedly withheld critical information from regulators,”