Wither always goes down and Does not fly

Its true on creative but no in survival

I try spawn using command (/summon wither.boss x y z) on survival and wither fly and attacks me.Wither hard to attack any mob like PC edition.

The wither flies for me in creative, 0.15.90.8
It seems that the wither needs a target to fly which it didn't have in 0.15.90.7 due to a bug so this can be marked as fixed I believe.

Fixed in build 5