[confirmed]Can unmanifest Dryad Arbor

[Korath]

Describe the Bug:
If you manifest a Dryad Arbor, you can turn it faceup by paying 0. (I manifested it with Temur War Shaman, after having put it on top of my library with a Roil Spout, but that shouldn't matter.)

Which card behaved improperly?
manifest_legacy()

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

What exactly should be the correct behavior/interaction?
It's stuck face-down, barring some external effect like Break Open, Skirk Alarmist, or Ixidor, Reality Sculptor.

202.1b Some objects have no mana cost. This normally includes all land cards, any other cards that have no mana symbols where their mana cost would appear, tokens (unless the effect that creates them specifies otherwise), and nontraditional Magic cards. Having no mana cost represents an unpayable cost (see rule 117.6). Note that lands are played without paying any costs (see rule 305, "Lands").

701.32b Any time you have priority, you may turn a manifested permanent you control face up. This is a special action that doesn't use the stack (see rule 115.2b). To do this, show all players that the card representing that permanent is a creature card and what that card's mana cost is, pay that cost, then turn the permanent face up. The effect defining its characteristics while it was face down ends, and it regains its normal characteristics. (If the card representing that permanent isn't a creature card or it doesn't have a mana cost, it can't be turned face up this way.)

Are any other cards possibly affected by this bug?
No. There aren't any other land creatures, and none of the seven non-land cards without mana costs are creatures. But just in case, it's more robust to check that cards_ptr[csvid].mana_cost[0] != '\0', instead of comparing against CARD_ID_DRYAD_ARBOR directly.