Silenced a flake8 warning.

../tests/shortcuts/views.py:45:1: E302 expected 2 blank lines, found 1
Fix another flake8 warning.

I don't agree with flake8 here about the right indentation, but as long as
we're using it, we should stick to it. I don't want to disable its hanging
indent checks just because of this case.
Fixed #23892 -- Made deconstructible classes forwards compatible