Python 2 has passed its sunset date, and many distributions are
withdrawing support for Python 2.
PEP 394 recommends distributions always install versioned interpreter
commands (e.g. `python3`), but does not make a recommendation about
whether or not an unversioned command (`python`) should exist, or what
version it should run.
It therefore seems advisable to explicitly run scripts using the
`python3` command, for scripts that are compatible with Python 3.
Here, we do this for Python scripts used by `run_tests`. For this to
work, some scripts have been updated in ways that will break Python 2
compatibility. But for some other scripts which were already compatible
with both Python 2 and 3, we have not yet removed Python 2
compatibility. There are also miscellaneous scripts that are not used by
`run_tests`, and these have not yet been updated to Python 3.
Signed-off-by: Matthew Brecknell <Matthew.Brecknell@data61.csiro.au>
Matthew Brecknell
Gerwin Klein