Fixing an error in helper balanced_reverse sorting

Found with rbx-head, Array#sort_by isn't a stable sort in rbx but
appears to be in most other Rubies. Thus the array

  [ [ '-', 1, 1 ],
    [ '-', 1, 2 ],
    [ '-', 2, 2 ] ]

would be sorted properly with the code

  #sort_by { |line| line[1] }

on most Rubies, but rbx might sort it as

  [ [ '-', 1, 2 ],
    [ '-', 1, 1 ],
    [ '-', 2, 2 ] ]

Changing the sort to

  #sort_by { |line| [ line[1], line[2] ] }

fixes this.

0 files changed, 0 insertions, 0 deletions