Avoid excluding fields in copyToLanguage
Given that a TCA column is using
'l10n_mode' => 'exclude' and creating a "free localization" of that record using DataHandler's
copyToLanguage command, the according field stays empty in the created localization.
$GLOBALS['TCA']['tt_content']['columns']['header']['l10n_mode'] = 'exclude';
The expected behavior would have been, that the accordings field is still duplicated once on creating the duplicate for a particular language.