Presolve does not alter model's Objective Sense, but will alter its copies'

[Joao-Dionisio]

This code (test.zip, adapted from atsp.py)

yields this output

I do not know if this is desired behavior, but I find it to be counterintuitive. A copied model should be equal to the model it's copying, but the original model seems to be maintained even after the presolve, resulting in different models. Without the presolve this issue does not arise.

EDIT: I don't want to flood the repository with issues, so I'll just make a quick comment that the model method self.getObjlimit() does not follow the camel case convention of the rest of the code.