Splatting MatchData bug?

$ /tmp/ruby-1.9/bin/ruby -v          
ruby 1.9.0 (2007-08-21 patchlevel 0) [i686-linux]
$ /tmp/ruby-1.9/bin/ri MatchData.to_a
--------------------------------------------------------- MatchData#to_a
     mtch.to_a   => anArray
------------------------------------------------------------------------
     Returns the array of matches.

        m = /(.)(.)(\d+)(\d)/.match("THX1138.")
        m.to_a   #=> ["HX1138", "H", "X", "113", "8"]

     Because +to_a+ is called when expanding +*+_variable_, there's a
     useful assignment shortcut for extracting matched fields. This is
     slightly slower than accessing the fields directly (as an
     intermediate array is generated).

        all,f1,f2,f3 = *(/(.)(.)(\d+)(\d)/.match("THX1138."))
        all   #=> "HX1138"
        f1    #=> "H"
        f2    #=> "X"
        f3    #=> "113"

$ /tmp/ruby-1.9/bin/irb 
irb(main):001:0> all,f1,f2,f3 = *(/(.)(.)(\d+)(\d)/.match("THX1138."))
=> [#<MatchData "HX1138" "H" "X" "113" "8">]
irb(main):002:0> all
=> #<MatchData "HX1138" "H" "X" "113" "8">
irb(main):003:0> f1
=> nil
irb(main):004:0> f2
=> nil
irb(main):005:0> f3
=> nil
irb(main):006:0> 
$ 

This works as documented in 1.8.5. Is it a bug?

-- 
Jos Backus
jos at catnook.com