It's broken
$ hg pull
pulling from *********************
keyring: keyring backend doesn't seem to work, password can not be restored. Falling back to prompts. Error details: cannot import name 'backend' from 'cryptography.hazmat.backends.openssl.backend' (/usr/lib/python3/dist-packages/cryptography/hazmat/backends/openssl/backend.py)
Edited by Marcin Kasperski