TYPO3 Core

While doing a copy & paste of a record after another record the method copyRecord makes use of some values of the target record.
These values are coming from fields that can be defined in TCA so basically there can be any field of any type and configuration as a source for such a value.
This works perfectly fine unless the value is NULL, which is a rare case in TYPO3 but can happen already.

While preparing the structured content stuff I noticed that necessary NULL values in colPos fields got replaced with 0.
This is due to the fact that copyRecords uses isset(), which returns FALSE for NULL values, where array_key_exists() would be the way to go.

Since this is not just a problem of structured content, I would like to fix that within a separate patch, to make sure the method as such is working as expected.