Attr: changed semantics of (internal) move method

This method needs to be used in places where freeing the src-pointer is
not possible, as it may be not allocated. If freeing is needed, it is
now in the responsibility of the caller. As it turns out this approach
is not even more useful, it is also less work, as it can be determined
from the fact, that adjusting the tests to the new behavior means
actually removing lines, that were previously working around the quirks,
that the old approach introduced.