(…) If you’re coming from Arch, you’re probably familiar with Arch Rollback Machine (ARM) . It holds old packages for much time ago, for various archs, organized in many different ways.
Python2, for example, is present here.
Download python2-2.7.9-1-x86_64.pkg.tar.xz to the local disk.
Then install downloaded package (downgrading python2 from 2.7.12 to 2.7.9) :
sudo pacman -U <path-to-package>
$ sudo pacman -U '/1st/dnl/python2-2.7.9-1-x86_64.pkg.tar.xz' [sudo] password for just: ********* loading packages... warning: python2-2.7.9-1 is up to date -- reinstalling resolving dependencies... looking for conflicting packages... Packages (1) python2-2.7.9-1 Total Installed Size: 70.03 MiB Net Upgrade Size: 0.00 MiB :: Proceed with installation? [Y/n] No, thanks, already done $