@rakeshkky reports:

After #2831 :

The ruamel.yaml 0.14.12 package and python 3.7 are not playing well together.I'm on Arch Linux and I've python 3.7.4 installed.

The dev.sh test is failing at the step pip3 install -r requirements.txt. See https://bitbucket.org/ruamel/yaml/issues/230/ruamelyaml-015-fails-install-on-python37, in the first comment, they linked to https://pypi.org/project/ruamel.yaml/0.14.12/#files which shows the ruamel.yaml 0.14.12 has no support for python 3.7.