In the following methods, skip casting of the argument to a path object ifthe argument has a `with_segments` attribute. In `PurePath`:`relative_to()`, `is_relative_to()`, `match()`, and `full_match()`. In`Path`: `rename()`, `replace()`, `copy()`, `copy_into()`, `move()`, and`move_into()`.Previously the check varied a bit from method to method. The `PurePath`methods used `isinstance(arg, PurePath)`; the `rename()` and `replace()`methods always cast, and the remaining `Path` methods checked for a private`_copy_writer` attribute.We apply identical changes to relevant methods of the private ABCs. Thisimproves performance a bit, because `isinstance()` checks on ABCs areexpensive.

This reverts commit89e05e4.