The burmese python is the only snake (that i know of) that has had its genome completely sequenced. Pygmy rattlesnakes and garter snakes have had part of theirs sequenced and they all point to the above mentioned. The odds of it being reversed are very slim.
Parthenogenesis is a strange anomaly in which the offspring (atleast of those observed in the case of one mother producing three litters) have had WW sex chromosomes. The outcome was fourty-some babies with WW. Unfortunately i'm on my phone and dont have the link but you can find a write-up about it online. It appears that only the W is copied and passed on to the offspring.
You bring up a good point though. Unfortunately limited studies have been done concerning reptile genomics so we only have so much to go off of.
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