[bug] conan.tools.env.EnvVars can't be initialized with scope=None

[bkarasm]

Describe the bug

When trying to use EnvVars class with scope=None as described in the docs I get an error

AttributeError: 'NoneType' object has no attribute 'startswith'

which is thrown by the deduce_subsystem() function from conans/client/subsystems.py.

Below is a code snippet from my conanfile.py. I'm trying to set GIT_LFS_SKIP_SMUDGE environment variable to skip LFS files when cloning git repo:

    def source(self):
        git = Git(self)
        env = Environment()
        env.define("GIT_LFS_SKIP_SMUDGE", "1")  # skip LFS files
        with env.vars(self, scope=None).apply():
            git.fetch_commit(...)

How to reproduce it

No response

[franramirez688]

Hi @bkarasm - Thanks for reporting this!

This issue should be solved in the current latest release 2.9.1.

Closing the issue as solved, but do not hesitate to reopen it if any other problem arises.

[bkarasm]

Hi @franramirez688, I was hoping that if I use scope=None in the source() method Conan won't default to build context. I'll create a separate issue to seek for assistance for the case I described.

[franramirez688]

Hi @bkarasm

It's not defaulting to build context, it's only supposing that the deduce_subsystem() function (and only for Windows) should use the build machine to deduce the subsystem if required. The rest is not using the build context at all.
Other changes are coming up to improve this flow because it's a bit confusing 😞