inconsitency in ruby string split

inconsitency in ruby string split

hiho little/big inconsistency in ruby core:
$ irb1.9.1 
irb(main):001:0> test1 = "  " # double space
=> "  "
irb(main):002:0> test1.split(" ",2) # single space
=> [""]
irb(main):003:0> test2 = "tt" # double t
=> "tt"
irb(main):004:0> test2.split("t",2) # single t
=> ["", "t"]