[confirmed]Mirrorweave turns face-down cards face-up

[Korath]

Describe the Bug:
If you control a face-down creature (Birchlore Rangers, but it shouldn't matter) and cast Mirrorweave targeting something else (Shivan Dragon, but it really shouldn't matter), the face-down card becomes a face-up Shivan Dragon (or whatever).

Which card behaved improperly?
Mirrorweave

Which update are you using? (date, name)Which type? (duel, gauntlet, sealed deck)
Dev 2bba4ec.

What exactly should be the correct behavior/interaction?
707.10. If a face-down permanent becomes a copy of another permanent, its copiable values become the copiable values of that permanent, as modified by its face-down status. Its characteristics therefore remain the same: the characteristics listed by the ability or rules that allowed it to be turned face down. However, if it is turned face up, its copiable values become the values it copied from the other permanent. See rule 706.3.

Are any other cards possibly affected by this bug?
Cytoshape, Shapesharer, Infinite Reflection, Polymorphous Rush, Deceiver of Form, and Permeating Mass. The only one of those I've tested is Cytoshape. (How come I can never remember any of them when I'm looking for an "arbitrary card becomes a copy of another arbitrary creature" effect? Mirrorweave's all kinds of inconvenient most of the time.)

Contrast with what happens when something face-up copies a face-down card.