Fedora 22 workstation did not install python 2 by default. libblockdev-1.1-2.fc23.x86_64 did not require python 2. libblockdev-1.3-4.fc23.x86_64 in updates now requires python 2. This is a regression.
It's actually not a regression, but a fix. See bug #1256758 for details. In rawhide, python* packages don't have to be installed, but to ensure everything works after update, the F23 packages need to require these. AFAICT, there's no way to ensure the clean update path and have those separate packages without requiring them from the 'libblockdev' package. If you know one, let me know and we can work on it. Meanwhile, I'm closing this as NOTABUG, because it works as expected.