userinfo=(s)[permalink][rdoc]自身の userinfo を設定します。
例:
require 'uri'
u = URI.parse('http://example.com/')
u.userinfo = 'hoge-san:jfae82kj'
p u.to_s #=> "http://hoge-san:jfae82kj@example.com/"
u.userinfo = 'oreore'
p u.to_s #=> "http://oreore:jfae82kj@example.com/"
u.userinfo = ['you', 'akakfd']
p u.to_s #=> "http://you:akakfd@example.com/"