There are some combination of objects and target types which we know
cannot be fulfilled. Return EINVALIDSPEC for those to signify that there
is a mismatch in the user-provided data and what the object model is
capable of satisfying.
If we start at a tag and in the course of peeling find out that we
cannot reach a particular type, we return EPEEL.
Any well-behaved program should write a descriptive message to the
reflog whenever it updates a reference. Let's make this more prominent
by removing the version without the reflog parameters.
