Script 790, python.vim--Vasiliev has been regenerated. It actually contained two different scripts -- one for python2 and one for python3, flip-flopping between them at every commit.
This has been worked around by placing the python3 script into its own branch. If you use script 790, delete your local copy and re-clone. It should work fine now.
Thanks go again to Jacobo de Vera for finding this.