dev-python/cherrypy has outsourced its web server component into dev-python/cheroot. dev-python/cheroot-6.3.0 has changed the API of cheroot.wsgi.Server, which is reflected in dev-python/cherrypy-18.1.0 . However, dev-python/cherrypy-18.1.0 only depends on >=dev-python/cheroot-5.9.1 , resulting in the error: ... File "/usr/lib/python3.6/site-packages/cherrypy/_cpwsgi_server.py", line 78, in __init__ peercreds_resolve_enabled=self.server_adapter.peercreds_resolve, TypeError: __init__() got an unexpected keyword argument 'peercreds_enabled' dev-python/cherrypy-18.1.0 should depend on >=dev-python/cheroot-6.3.0 . Currently the required version of cheroot is not in the tree. I have filed bug 679810 for that.
setup.py has cheroot>=6.2.4 in install_requires, and the current ebuild matches that.