FIX: zenspider said: does it really take an IO?
passed to a method called open?!? that seems stupid.
# File lib/rubygems/package.rb, line 35
def self.open(io, mode = "r", signer = nil, &block)
tar_type = case mode
when 'r' then TarInput
when 'w' then TarOutput
else
raise "Unknown Package open mode"
end
tar_type.open(io, signer, &block)
end