PR: Put the sys.prefix in the config search path

[pelson]

Description of Changes

This change puts sys.prefix on the config search path. With this change we have the option of providing a centrally managed spyder installation which can be pre-configured without setting global (machine-wide) config.

The use case that this comes from:

I want to be able to provide a spyder installation to a large number of users (200+) who have all got a specific NFS drive mounted on their Linux (Centos) machines. I therefore cannot setup a config in /etc/, and cannot control the user's ~/.config; I therefore want to be able to put a config in {sys.prefix}/etc/spyder/spyder.ini and it affect the global config (which can be overridden by the user config, should a user so choose).

In my case, I wanted to provide a spyder installation which is pre-configured to use a specific interpreter by default (different from the spyder interpreter). I therefore put the following config file in place:

$ which spyder
/home/pelson/github/spyder/spyder/env/bin/spyder

$ cat /home/pelson/github/spyder/spyder/env/etc/spyder/spyder.ini 
[main_interpreter]
custom_interpreter = /tmp/spyder-kernel-env/bin/python
executable = /tmp/spyder-kernel-env/bin/python
default = False
custom = True

$ rm -rf ~/.config/spyder-py*

$ spyder   # correctly uses the configured environment (/tmp/spyder-kernel-env/bin/python)

Affirmation

By submitting this Pull Request or typing my (user)name below,
I affirm the Developer Certificate of Origin
with respect to all commits and content included in this PR,
and understand I am releasing the same under Spyder's MIT (Expat) license.

I certify the above statement is true and correct:

@pelson

[ccordoba12]

Hey @pelson, nice to see you here and thanks a lot for your contribution!

We'd like to include it in our next release in the Spyder 5 series. For that, please make your branch to derive from our 5.x branch (instead of master), with the following commands:

git checkout 5.x
git checkout feature/sys_prefix_config
git rebase --onto 5.x master feature/sys_prefix_config
git push -f origin feature/sys_prefix_config

Other than that, the change seems sensible, so I'm ok with it.

[pelson]

nice to see you here and thanks a lot for your contribution!

Good to see you also! It has been a long time!

We'd like to include it in our next release in the Spyder 5 series

Great, I've rebased. 👍

[ccordoba12]

Thanks @pelson!

[pelson]

🥳 - thank you for reviewing/merging so quickly. Happy to have my first commit on spyder! 👍

[ccordoba12]

No prob, hope more commits will come in the future!