ruby-1.7.3 tag

[avsej]

Hi

It is true that there no such tag in ruby/ruby repository, but thanks to daily version.h update, you can easily find the correct tree, which match the version described in the book

https://github.com/ruby/ruby/tree/c0d0125bc70d7fbde34bea82f9c06bf6cb57b2eb

I think it will be better that having this repo. Or you can fork and push the tag. Or create branch ruby-1.7.3 and make it default in the repo settings

Thank you.