message: Fix fusing into a custom-call fusion in multiple steps
diff: @@ -663,10 +663,6 @@ bool InstructionFusion::ShouldFuse(HloInstruction* consumer,
  return false;
  }
  - if (consumer->opcode() == HloOpcode::kFusion && consumer->IsCustomFusion()) {
  - return false;
  - }
  -
  if (producer->CouldBeBitcast() &&
  // We can't fuse parameters anyhow, so we leave the user unfused to become
  // a bitcast. If the operand is not a parameter, we would break a
  