Add variables ENABLED_PYTHON3_PACKAGES and DISABLED_PYTHON3_PACKAGES to
work like ENABLED_SERVICES and DISABLED_SERVICES and to manage which
packages are installed using Python 3. Move the list of whitelisted
packages in pip_install to the default for ENABLED_PYTHON3_PACKAGES,
except swift which is not enabled by default for now.
Add enable_python3_package and disable_python3_package functions to make
editing the variables from local.conf easier.
Add python3_enabled_for and python3_disabled_for functions to check the
settings against packages being installed by pip.
Update pip_install to check if python3 is disabled for a service, then
see if it is explicitly enabled, and only then fall back to looking at
the classifiers in the packaging metadata.
Update pip_install messages to give more detail about why the choice
between python 2 and 3 is being made for a given package.
Change-Id: I69857d4e11f4767928614a3b637c894bcd03491f
Signed-off-by: Doug Hellmann <doug@doughellmann.com>
94129c7d02