For post-loop tests use Kernel#loop over begin/end/while

For post-loop tests use Kernel#loop over begin/end/while or begin/end/until.

Based on Matz's comments:
http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-core/6745

And also:
http://rosettacode.org/wiki/Loops/Do-while#Ruby