message: Restore registration for variable merger pass.
diff: @@ -30,6 +30,8 @@ REGISTER_OPTIMIZATION(OptimizationPassRegistry::PRE_PLACEMENT, 34,
  EncapsulateTPUComputationsPass);
  REGISTER_OPTIMIZATION(OptimizationPassRegistry::PRE_PLACEMENT, 39,
  ExtractOutsideCompilationPass);
  +REGISTER_OPTIMIZATION(OptimizationPassRegistry::POST_REWRITE_FOR_EXEC, 0,
  + VariableMergerPass);
  } // namespace
  } // namespace tensorflow
  