message: Temporarily relax restriction on mhlo.while terminator
  Some internal tests are failing, so relaxing this restriction
  temporarily while we investigate.
diff: @@ -578,8 +578,7 @@ def HLO_CaseOp: HLO_Op<"case", [
  def HLO_WhileOp: HLO_Op<"while", [
  RecursiveSideEffects,
  - SameOperandsAndResultType,
  - SingleBlockImplicitTerminator<"ReturnOp">
  + SameOperandsAndResultType
  ]>, BASE_HLO_WhileOp {
  let arguments = (ins HLO_TensorOrTuple:$val);
  