[racket-dev] impersonate-struct with only impersonator properties

The documentation for impersonate-struct and chaperone-struct differ
in the fact that chaperone-struct explicitly says that only
impersonator properties are not allowed. But the implementation
doesn't allow it for either of them. Either the documentation or the
implementation is wrong.

What is the reasoning behind the implementation? Is it so that code
that doesn't have access to the struct cannot add properties, because
that prevents code that does have access to the struct from being able
to set only impersonator properties (Which is what I am trying to do).
Thus a solution for me is to wrap an accessor as well but that seems
unnecessary.