Hit Pacman with a stick if necessary:

• Pacman can get confused about OS version:
  • e.g., "Platform [Debian-] is not yet supported"
• pacman -help
• pacman -platforms
• pacman -pretend-platform <platform> -get <package>, e.g.,

  pacman -pretend-platform Debian-3.1 -get \
      http://vdt.cs.wisc.edu/vdt_1310_cache:GSIOpenSSH