The release of pip10 has shown up a few issues here
Firstly, pip10 now refuses to overwrite distutils installed packages,
which includes "python-virtualenv" on centos. History has shown us
that we want the packages installed and overwritten, to avoid the
packages coming back and messing things up.
Pre-install all the packages, then list the files in the packages with
"rpm" directly and remove them. This way pip is happy to install.
We need to take better account of the package names for this; on
Fedora things have switch to "python2-virtualenv" instead of
"python-virtualenv" and we can't use an alias to list the package
contents.
This also highlighted that python2-pip is in EPEL for centos, so
enable that when we install it. Make the epel element a no-op for non
centos/rhe distros.
There is a related change in recent fedora that python3 now installs
binaries into /usr/local/bin. There are commented swizzles in here to
ensure we retain the status quo of "pip" and "virtualenv" both being
python2 based, with the python3 versions being called explicitly
"pip3" and "virtualenv3" respectively.
Change-Id: I2ffdd9f615ae6b00428c17249e4f216774991b99
b423292cd0