Is this a bug?

$ cat bug.rb
require 'optparse'

OptionParser.new do |prsr|
   prsr.on("-a",
           "please use the",
           "-b option instead")
#          ^
# insert a space above the caret to prevent
# detection of -b as an option.
#

   prsr.on("-b", "--foo-bar")

   prsr.parse!(ARGV)
end

__END__

$ ruby bug.rb -h
Usage: bug [options]
     -a, -b option instead            please use the
         --foo-bar