http_post (and possibly others) does not work when instantiating Curl::Easy.new without arguments

[vrsean]

$ bundle show curb
/Users/SeanHoran/.rvm/gems/ruby-2.2.2@sbas/gems/curb-0.8.8

$ cat .ruby-version
2.2.2

$ bundle exec irb
-- snipped --
2.2.2 :011 > require 'curb'
=> true
2.2.2 :012 > ldap_url # censored, doesn't work without :8080 either
=> "http://server.mycompany.com:8080/j_acegi_security_check"
2.2.2 :013 > LDAP_USERNAME
=> "jenkinsbuilder"
2.2.2 :014 > LDAP_PASSWORD # censored
=> "*********"
2.2.2 :015 > client = Curl::Easy.new
=> #Curl::Easy
2.2.2 :016 > client.http_post(ldap_url, Curl::PostField.content('j_username', LDAP_USERNAME), Curl::PostField.content('j_password', LDAP_PASSWORD))
Curl::Err::CurlError: No URL supplied
from /Users/SeanHoran/.rvm/gems/ruby-2.2.2@sbas/gems/curb-0.8.8/lib/curl/easy.rb:67:in add' from /Users/SeanHoran/.rvm/gems/ruby-2.2.2@sbas/gems/curb-0.8.8/lib/curl/easy.rb:67:in perform'
from (irb):16:in http_post' from (irb):16 from /Users/SeanHoran/.rvm/rubies/ruby-2.2.2/bin/irb:11:in

'

This is contrary to the docs and source ... any idea what's up?