Message 95117 - Python tracker

It would be very useful to have an environment variable $PYTHONWARNINGS,
tied to the -W option for silencing various warnings (most importantly,
DeprecationWarnings).

Use case: a test suite running many subprocesses, testing that those
subproc output is clean.  DeprecationWarnings cannot easily be
suppressed by passing -W flags all around or using liberally sprinkled
filterwarnings().  Setting $PYTHONWARNINGS once and for all to silence
all processes would be very useful.