message: If sphinx_rtd_theme_chm_friendly directory is missing, use normal theme
diff: @@ -320,8 +320,11 @@ texinfo_documents = [
  #texinfo_no_detailmenu = False
  # custom theme based on sphinx_rtd_theme
  +if os.path.isdir('sphinx_rtd_theme_chm_friendly'):
  html_theme = "sphinx_rtd_theme_chm_friendly"
  html_theme_path = ["."]
  +else:
  + html_theme = "sphinx_rtd_theme"
  html_context = {
  'show_source': False,
  