Same with me actually, do you run windows? I always thought it was
already required (noob)
I run all 3 
Net/http is usually not already required. you might have it required
previously in the session or maybe in your .irbsc file. If you are in
the script/console session in rails, then rails might have it required
before you. Btw, Requiring something returns something only the first
time, afterward it returns false.
Diego Scataglini