Here's the command that I used and the results. I ran this on a RPi Zero W.
sudo pacman -S python-pip
resolving dependencies...
looking for conflicting packages...
Packages (6) python-appdirs-1.4.3-1 python-packaging-16.8-2 python-pyparsing-2.2.0-1
python-setuptools-1:38.5.2-1 python-six-1.11.0-1 python-pip-9.0.1-3
Total Download Size: 0.28 MiB
Total Installed Size: 9.09 MiB
:: Proceed with installation? [Y/n] y
:: Retrieving packages...
error: failed retrieving file 'python-setuptools-1:38.5.2-1-any.pkg.tar.xz' from mirror.archlinuxarm.org : The requested URL returned error: 404
warning: failed to retrieve some files
error: failed to commit transaction (unexpected error)
Errors occurred, no packages were upgraded.
I went to the mirror and it looks like the version of python-setuptools has changed and therefore pacman cannot install.
Please help.