There is actually very little information on the subject of licensing with pywallet, but from what I've seen, Joric created pywallet and then Jackjack made a fork of it, although apparently Joric's original license according to his repository on Google is BSD.
To be perfectly honest with you, I don't have much experience in open source development and this was actually my very first fork of an existing code ever. So, I don't really know what is the correct procedure here. Should I just assume the license is BSD and therefore mark my fork as BSD license as well on Github?
On a relating note: I have been working more with my updated PyWallet. I found another corrupted wallet.dat file which could not be processed by any previous versions of PyWallet, so I made improvements to my fork and it is now able to handle that type of file corruption as well and recover data from it. Debug logging was also improved.