Add a note to the Python pages regarding upgrading pip
|Reported by:||Douglas R. Reno||Owned by:||blfs-book|
As of Python-2.7.16 and Python-3.7.3, an upgrade of pip (either pip2 or pip3) will overwrite the opposite set of programs. As an example, running 'pip2 --upgrade pip' will remove /usr/bin/pip3 and /usr/bin/pip3.7.
In order to fix this, the user has to run 'python3 -m pip install --force pip'. This is because pip is already listed as installed in /usr/lib/python3.7/site-packages/pip, but it isn't able to be run via standard means (you have to run python3 -m pip install <module_name>).
To overcome this, since we still have to support both python versions, I think a note should be added to both Python pages containing instructions for repairing upgrades of pip that cause problems such as this (18.0.3 ships with Python-2.7.16, and this was discovered while upgrading to 19.1 which adds the warning about Python deprecation).
TL;DR - add a note explaining to run 'python3 -m pip install --force pip' to Python3 (and a Python2-based note to Python2) in the event that pip is upgraded.