ISTM that the patch is trying to do too many things at once:
1) increase the test coverage, possibly fixing some bugs discovered while doing so;
2) refactor the tests to use the correct assert methods;
3) get rid of old code, and do some refactoring in copy.py;

I'm not sure any of the changes in copy.py is necessary to make the test suite pass, even after the additions you included in the patch (I haven't tested though).  If this is the case, the refactoring/cleanup of copy.py should IMHO be committed separately.
For the tests it's probably fine to commit both the additions and the refactoring together (i.e., it's not worth wasting time splitting the patch).