Change `deleted` to `was_deleted` and fix wrong parentheses
Change `deleted` to `was_deleted` and fix wrong parentheses

Note that the wrong parentheses yielded asserted the truthness of the
generator `(all(o) for o in objects)`, which is trivial.  Thus, the
tests never actually verified anything.

agdsn/pycroft,lukasjuhrich/pycroft,agdsn/pycroft,lukasjuhrich/pycroft,agdsn/pycroft,agdsn/pycroft,lukasjuhrich/pycroft,agdsn/pycroft,lukasjuhrich/pycroft