Data definitely belong in the repository, not only because you want to version your assets too, but also because chances are your code at time T is also meant t

Data definitely belong in the repository, not only because you want to version your assets too, but also because chances are your code at time T is also meant to work with your data at the same time T - so you don't even attempt to do stuff like trying to figure out when some bug was introduced with current data (that could cause or hide the bug or your older code not even working with the current data). You could try to put your data in some other repository, but since you are versioning that data anyway, that introduces additional pointless complexity and besides the code is useless without the data to work with - so just stick them together and be done with it. If your VCS cannot handle that, instead of having it dictate your workflow towards an inferior solution, change your VCS. At least as far as games are concerned, data and code are interwoven and any other approach is guaranteed to either fail or produce unnecessary and easily avoidable complications.