Go to: http://api.rubyonrails.org/classes/ActiveRecord/Migration.html
It opens without problems.
Go to: http://code.djangoproject.com/wiki/SchemaEvolution
This page works also. There is a link to the Rails page about half way down - click it. The rubyonrails.org page will now fail with "Precondition failed" (try a refresh if it does open, as your browser should have already cached it).
Try both methods in separate tabs: you can refresh both rubyonrails.org URLs all day long, but the tab with the djangoproject.com Refer header will always fail in the same way.
Now that, my friends, is messed up.
I will let you draw your own conclusions.
