Release of pyyaml 3.13 seems to have fixed install issues on Python 3.7.
Release of pyyaml 3.13 seems to have fixed install issues on Python 3.7.

jaraco/jaraco.classes,jaraco/irc,yougov/pmxbot,jaraco/rwt,yougov/librarypaste,jazzband/inflect,jaraco/jaraco.functools,hugovk/inflect.py,pytest-dev/pytest-runner,cherrypy/cheroot,jaraco/hgtools,python/importlib_metadata,jaraco/jaraco.path,pwdyson/inflect.py,jaraco/keyring,jaraco/portend,jaraco/jaraco.text,jaraco/jaraco.context,jaraco/tempora,jaraco/calendra,yougov/pmxbot,yougov/pmxbot,jaraco/zipp,jaraco/jaraco.collections,jaraco/jaraco.stream,jaraco/jaraco.itertools,yougov/librarypaste,jaraco/backports.functools_lru_cache,jaraco/jaraco.logging