Make all self-move operations raise `IllegalDestination` error by althonos · Pull Request #549

Make all self-move operations raise `IllegalDestination` error by althonos · Pull Request #549 · PyFilesystem/pyfilesystem2

Type of changes

Bug fix
New feature
Tests

Checklist

I've run the latest black with default args on new code.
I've updated CHANGELOG.md and CONTRIBUTORS.md where appropriate.
I've ~~added~~ updated tests for new code.
I accept that @PyFilesystem/maintainers may be pedantic in the code review.

Description

As discussed with @lurch in #547, this PR makes all self-move operations raise IllegalDestination instead of being silent. In fs.move.move_file, DestinationExists takes priority if overwrite is False.