To follow up, with my test builds from comment 36:
FROM trusty: WORKS TO python2 in t/x/b/g FAILS to python2 in f FAILS to python3 in t/x/b/f/g
FROM xenial: WORKS TO python2 in t/x/b/g FAILS to python2 in f FAILS to python3 in t/f WORKS TO python3 in x/b/g
FROM bionic: WORKS TO python2 in t/x/b/f/g WORKS TO python3 in t/x/b/f/g
FROM focal: WORKS TO python2 in t/x/b/f/g WORKS TO python3 in t/x/b/f/g
FROM focal: FAILS TO python2 in t/x/b/f/g WORKS TO python3 in t/x/b/f/g
To follow up, with my test builds from comment 36:
FROM trusty:
WORKS TO python2 in t/x/b/g
FAILS to python2 in f
FAILS to python3 in t/x/b/f/g
FROM xenial:
WORKS TO python2 in t/x/b/g
FAILS to python2 in f
FAILS to python3 in t/f
WORKS TO python3 in x/b/g
FROM bionic:
WORKS TO python2 in t/x/b/f/g
WORKS TO python3 in t/x/b/f/g
FROM focal:
WORKS TO python2 in t/x/b/f/g
WORKS TO python3 in t/x/b/f/g
FROM focal:
FAILS TO python2 in t/x/b/f/g
WORKS TO python3 in t/x/b/f/g