old_contents: from authorization import has
  from adhocracy.model import Text
  
  import page
  
  
  def edit(check, p, variant):
      check.valid_email()
      check.other('instance_without_norms', not p.instance.use_norms)
      check.other('instance_frozen', p.instance.frozen)
      check.other('variant_is_none', variant is None)
      if has('instance.admin'):
          return
      page.edit(check, p)
  
      check.other('page_has_no_variants_and_variant_is_not_head',
                  not p.has_variants and variant != Text.HEAD)
  
      if not has('page.edit_head'):
          check.other('page_function_is_norm_and_variant_is_head',
                      p.function in p.LISTED and variant == Text.HEAD)
  
  
  def delete(check, p, variant):
      check.valid_email()
      check.other('variant_is_none', variant is None)
      check.other('variant_is_head', variant == Text.HEAD)
      if has('instance.admin'):
          return
      page.delete(check, p)
  
new_contents: from authorization import has
  from adhocracy.model import Text
  
  import page
  
  
  def edit(check, p, variant):
      check.valid_email()
      check.other('instance_without_norms', not p.instance.use_norms)
      check.other('instance_frozen', p.instance.frozen)
      check.other('variant_is_none', variant is None)
      if has('instance.admin'):
          return
      page.edit(check, p)
  
      check.other('page_has_no_variants_and_variant_is_not_head',
                  not p.has_variants and variant != Text.HEAD)
  
      if not has('page.edit_head'):
          check.other('page_is_listed_and_variant_is_head',
                      p.function in p.LISTED and variant == Text.HEAD)
  
  
  def delete(check, p, variant):
      check.valid_email()
      check.other('variant_is_none', variant is None)
      check.other('variant_is_head', variant == Text.HEAD)
      if has('instance.admin'):
          return
      page.delete(check, p)
  
subject: fix page.edit_head error msg