Only one point should be used to create a reference rotation for other
points to follow. Using two caused the resulting twist to be
asymmetric, especially noticeable on symmetrical, cyclic curves.
An update to [0] which broke curve_to_mesh & deform_modifiers tests,
now this change only applies to cyclic curves as the final result was
much greater for non-cyclic curves because of a difference between how
end-point directions are calculated (see code-comments for details).
Alternate fix to D11886 which caused T101843.
[0]: 36a82314a0.
564673b8ea