isnt Pine supposed to be slightly noxious to snakes? something nasty in it or so i`m led to believe
in any case, what ever substrate you use,, most important things are -
temp is right and temp gradient is right
humidity is tolerable
there is water to drink
several places to hide
and you feed it in another container if possible... a large tupperware box or something... lst thing you want is for you new snake to swallow repti bark or aspen shavings with his meal... that leads to problems.. even fatalities......
apart from the feeding thing and noxious pine vapours, the only substrates to avoid are the sand-like ones as they tend to be dry and irritate the snakes skin
allegedly
i`m drunk so i could be wrong