An upcoming change needs a feature from Git 2.10, which Ubuntu 16.04
LTS lacks. Since Python 3.5 reached end of life with the 3.5.10
release on 2020-09-05, it's been unsupported by its maintainers for
nearly 2 years anyway.
Change-Id: I0369c29baa344c4dc76eaa47b3467b6117eb933c