redirectable?

# File lib/open-uri.rb, line 193
  def OpenURI.redirectable?(uri1, uri2) # :nodoc:
    # This test is intended to forbid a redirection from http://... to
    # file:///etc/passwd.
    # However this is ad hoc.  It should be extensible/configurable.
    uri1.scheme.downcase == uri2.scheme.downcase ||
    (/\A(?:http|ftp)\z/i =~ uri1.scheme && /\A(?:http|ftp)\z/i =~ uri2.scheme)
  end