Can't use rails_upgrade plugin on Windows due to missing fork() function

I'm on Windows....and I can't get anything to work with this plugin:
http://github.com/rails/rails_upgrade

If I run rake rails:upgrade:check, for example, I get this:

rake aborted!
fork() function is unimplemented on this machine

What a drag! I heard that Ruby's fork() function is unimplemented on
Windows...
DOES THAT MEAN I CAN'T USE THE PLUGIN?

If you have any insights, please helpppp!

Ruby's fork() function isn't "unimplemented" on windows, fork() is an
function provided by the OS on Unix and Unix-like OS'es (e.g. Linux,
OS X, etc, etc.)