calcurse-caldav: Avoid corrupting the sync DB
calcurse-caldav: Avoid corrupting the sync DB

When importing an iCal event via calcurse fails (i.e. does not return a
single object hash), do not write anything to the synchronization
database instead of blindly appending the entry, thereby potentially
corrupting the database.

Signed-off-by: Lukas Fleischer <c9ca73f8336dcfb037ec2c2abf52d80a6847a5cd@calcurse.org>

lfos/calcurse,lfos/calcurse,lfos/calcurse