I found that in 18.4.0 I had missed a couple of spots that needed version specs to setup. (2.1b2a requires a version argument to setup; I believe this was an error and they will fix it before 2.1 final, but for now I wanted it to work and it won't hurt as the information is not used) I need a volunteer to figure out what changes are needed to make 18.4 compile with Pythons before 2.1. I think all that is needed are some #if's in the right place and then some logic in the setup to set the appropriate macro when the python version is too early. But I don't have time to do it and the new "bug release" policy for Python will increase the number of stragglers who don't go to new versions.