Pip installs module successfully but it doesn't install?

Question

linux

Good afternoon!
I encountered a very strange bug (?) in python pip. I'm using Python 3.7.4 built from source and installed as altinstall. At some point, modules stopped being installed in virtual environments, and the installation seems to be successful, but nothing happens. Even pip itself is not updated! For example:

(myvenv) [[email protected] myvenv]$ pip install --upgrade pip
Collecting pip
  Downloading https://files.pythonhosted.org/packages/30/db/9e38760b32e3e7f40cce46dd5fb107b8c73840df38f0046d8e6514e675a1/pip-19.2.3-py2.py3-none-any.whl (1.4MB)
    100% |████████████████████████████████| 1.4MB 6.0MB/s 
Installing collected packages: pip
Successfully installed pip-19.2.3
You are using pip version 19.0.3, however version 19.2.3 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.

(myvenv) [[email protected] myvenv]$ pip install --upgrade pip
Collecting pip
  Using cached https://files.pythonhosted.org/packages/30/db/9e38760b32e3e7f40cce46dd5fb107b8c73840df38f0046d8e6514e675a1/pip-19.2.3-py2.py3-none-any.whl
Installing collected packages: pip
Successfully installed pip-19.2.3
You are using pip version 19.0.3, however version 19.2.3 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.

(myvenv) [[email protected] myvenv]$ pip -V
pip 19.0.3 from /home/groosha/PycharmProjects/myvenv/lib/python3.7/site-packages/pip (python 3.7)

As you can see from the listing above, there are no errors, but the changes are not applied. With the installation of third-party libraries (for example, requests), the same thing. "Successfully installed" but not really.
OS Manjaro 18.1.0 Juhraya. Already tried rebuilding Python, same thing.
Update: Strange situation. According to my observations, what I install through the "wenvian" pip is installed as if from under /usr/bin/pip, although, it would seem, what does it have to do with it?
But at the same time, being in venv, the printenv command shows that the "venv" binaries directory is in the first place in PATH, i.e. pip should cling from there. But no.

Answer 1

While searching for a solution, I came across this question from StackOverflow. Remarkably, the person also has Manjaro Linux.
On my work machine, I found the file /etc/pip.conf mentioned in the link above , where it was specified (by whom?) user = True. Changed it to False and the problem disappeared.
By the way, on a neighboring laptop with exactly the same Manjaro, there is no /etc/pip.conf file , nor is there the original problem.
I'd appreciate it if someone could explain why editing that file helped resolve the issue.