@wide-energy-11069 : not sure why it doesn't explode, but:

register('--ignore-patterns', advanced=True, type=list, fromfile=True,
             default=['.*/', rel_distdir, 'bower_components/', 'node_modules/', '*.egg-info/'],
             removal_version='1.3.0.dev0', removal_hint='Use --build-ignore instead.',
             mutually_exclusive_group='build_ignore', help='See help for --build-ignore.')