Looks like it's just a very nice Okee with a bit of an aberrant pattern.
Could be incubation temperatures/conditions.
Could be a random chance of genetics.
Could even be some sort of hybrid with another colubrid species way way way back in the gene pool - so far back that it looks essentially corn.
Unless they breed it and get some sort of reliable results (i.e. babies come out looking like that, or babies bred to each other/to this animal come out looking like that) I wouldn't assume it's anything inheritable genetic.