old_contents: # -*- coding: utf-8 -*-
  from contextlib import contextmanager
  
  import maya.app.renderSetup.model.renderSetup as renderSetup
  from maya import cmds
  
  
  @contextmanager
  def enabled_render_layers():
      old_layer = cmds.editRenderLayerGlobals(query=True, currentRenderLayer=True)
      try:
          rs = renderSetup.instance()
  
          def switchToLayer(layer):
              def _switch():
                  rs.switchToLayer(layer)
              return _switch
  
          enabled_layers = []
          for layer in rs.getRenderLayers():
  
              layer.switchToLayer = switchToLayer(layer)
              if layer.isRenderable():
                  enabled_layers.append(layer)
  
          yield enabled_layers
      finally:
          cmds.editRenderLayerGlobals(currentRenderLayer=old_layer)
  
new_contents: # -*- coding: utf-8 -*-
  from contextlib import contextmanager
  
  import maya.app.renderSetup.model.renderSetup as renderSetup
  from maya import cmds
  
  
  @contextmanager
  def enabled_render_layers():
      old_layer = cmds.editRenderLayerGlobals(
          query=True,
          currentRenderLayer=True,
      )
      try:
          rs = renderSetup.instance()
  
          def switchToLayer(layer):
              def _switch():
                  rs.switchToLayer(layer)
              return _switch
  
          enabled_layers = []
          for layer in rs.getRenderLayers() + [rs.getDefaultRenderLayer()]:
  
              layer.switchToLayer = switchToLayer(layer)
              if layer.isRenderable():
                  enabled_layers.append(layer)
  
          yield enabled_layers
      finally:
          cmds.editRenderLayerGlobals(currentRenderLayer=old_layer)
  
subject: Fix defaultRenderLayer was not included when blasting all layers.