Random MarkerIndex spec failure

[nathansobo]

Random seed: 1438117651498

MarkerIndex
  randomized mutations
    it maintains data structure invariants and returns correct query results
      Expected { row : 18, column : 6 } to equal { row : 11, column : 12 }, '(Marker 9 start; Seed: 1438117651498)'. (spec/marker-index-spec.coffee:341:46)
      Expected { row : 18, column : 6 } to equal { row : 11, column : 12 }, '(Marker 11 start; Seed: 1438117651498)'. (spec/marker-index-spec.coffee:341:46)
      Expected set (10 13 14 15 16) to have item 11. (Seed: 1438117651498) (spec/marker-index-spec.coffee:347:70)
      Expected set (10 14 15 16) to have item 11. (Seed: 1438117651498) (spec/marker-index-spec.coffee:347:70)
      Expected set (10 13 14 15 16) to have item 11. (Seed: 1438117651498) (spec/marker-index-spec.coffee:347:70)
      Expected set (10 14 15 16) to have item 11. (Seed: 1438117651498) (spec/marker-index-spec.coffee:347:70)

/cc @maxbrunsfeld