python 3.9.0 is soon to be released.

check if borg works on py39, try manually and also run our tests.

add it to tox.ini, travis-ci, vagrant boxes, setup.py (metadata).

My primary use case is to mount backups and then mount virtual machine images from inside them; but the latter cannot be achieved unless root is able to access the files.

This can be achieved by doing the mounting as root, but it is less convenient than just doing it as the same user.

Preferably the support would include also other standard mount options, as outlined in the fuse(8) manual pa

Is your feature request related to a problem? Please describe.
Currently, MapType are not supported for Spark DataFrames

Describe the solution you'd like
Add support for MapType Spark DataFrame columns

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other co