ln2 value is _math.c (cpython)

[Gribouillis]

I think the answers you got from stackoverflow are correct. The hard coded value is not log(2) but log(2) truncated to the ieee754 representation on presumably 64 bits.

Concerning wolfram alpha's result here is what python says

>>> from math import log
>>> x = 0.6931471805599453094172321214581
>>> x == log(2)
True
>>> y = 6.93147180559945286227E-01
>>> y == log(2)
True

so there is no difference in ieee754 representation on 64 bits.