Cats Summoned by Spawn Cat egg are Untamable

The Spawn Cat eggs introduced in this snapshot spawn cats are not tamed to the person that summoned them, nor are they tameable.

They also will not breed with other cats spawned by the egg. Hearts appear, but they don't react.

The cats also do not act like normal tamed cats: sitting on top of chests or beds.

May be related to this bug: MC-52954