Fatal error from BaseIPN cancelled method when MySQL mode is STRICT_TRANS_TABLES

The cancelled method is retrieving all contribution object values from the DB and then saving them back to the DB. This doesn't work properly for date fields - they need to be converted from ISO to MySQL before saving to DB.

If MySQL server is not running with a "strict" mode, the save works but the dates are truncated (only the YYYY part is saved). See screenshot for how this looks in the user interface.

In "strict" mode, the save fails with:

1292 ** Incorrect datetime value: '2012' for column 'receive_date'