[master] Write hardcoded salt version before building when running "setup.py --with-salt-version=xxxx"

[meaksh]

What does this PR do?

This PR fixes an issue we detected when building Salt with setup.py script and making use of --with-salt-version parameter to hardcode an specific Salt version:

# python3 setup.py --with-salt-version=9999 build
# python3 setup.py --with-salt-version=9999 install

After running the above commands, the generated "egg-info" metadata for the built package is not reflecting the specified version but instead it is calculating it without respecting what it was provided via --with-salt-version parameter:

# cat salt.egg-info/PKG-INFO | grep ^Version
Version: 3006.2+1103.g2cc6113338

Previous Behavior

As mentioned, I got a different version than the specified:

# python3 setup.py --with-salt-version=9999 build
...
# python3 setup.py --with-salt-version=9999 install
...
Finished processing dependencies for salt==3006.2+1103.g2cc6113338
# cat salt.egg-info/PKG-INFO | grep ^Version
Version: 3006.2+1103.g2cc6113338

New Behavior

After this PR, I get the expected version in the generated egg-info:

# python3 setup.py --with-salt-version=9999 build
...
# python3 setup.py --with-salt-version=9999 install
...
Finished processing dependencies for salt==9999.0
# cat salt.egg-info/PKG-INFO | grep ^Version
Version: 9999.0

Merge requirements satisfied?

[NOTICE] Bug fixes or features added to Salt require tests.

• Docs
• Changelog - https://docs.saltproject.io/en/master/topics/development/changelog.html
• Tests written/updated

Commits signed with GPG?

Yes

[s0undt3ch]

Be advised that we want to move away from setup.py and all of customizations we did there for Salt.
No exact date or release for that but an fyi, to try and divert from using it.

[meaksh]

Be advised that we want to move away from setup.py and all of customizations we did there for Salt. No exact date or release for that but an fyi, to try and divert from using it.

Thanks for the note! 👍

[dwoz]

@meaksh You can set the salt version by creating salt/_version.txt which is what we do in our official builds of Salt. Is there some reason that will not work for you?

[meaksh]

@meaksh You can set the salt version by creating salt/_version.txt which is what we do in our official builds of Salt. Is there some reason that will not work for you?

Hey @dwoz, manually creating salt/_version.txt would work as well, but IIUC the usage of --with-salt-version parameter on setup.py should create the salt/_version.txt automatically (if not existing) with the given version passed as argument.