Normally, if we project from a mutable class ivar or global variable, we'll
load a copy in a tight access scope and then project from the copy, in order to
minimize the potential for exclusivity violations while working with classes and
copyable values. However, this is undesirable when a value is move-only, since
copying is not allowed; borrowing the value in place is the expected and only possible
behavior. rdar://105794506
