The LaTeX is untested (well, so is the new API, for that matter).
Note that I also changed NULL to get spelled consistently in concrete.tex.
If that was a wrong thing to do, Fred should yell at me.
hoped it would be, but not too bad. A test had to change:
time.__setstate__() can no longer add a non-None tzinfo member to a time
object that didn't already have one, since storage for a tzinfo member
doesn't exist in that case.