Add username/email to bare git config in repo

[justice-adams-apple]

Add a fake git username/password to the update_checkout tests so they don't fail in differently configured git environments. Currently if a user doesn't have a global email/username setup in their git config the tests will fail with

*** Please tell me who you are.

Run

  git config --global user.email "[email protected]"
  git config --global user.name "Your Name"

to set your account's default identity.
Omit --global to set the identity only in this repository.

This PR sets the config for the local mock repository accordingly and ensures that the test is self contained and doesn't rely on the end-users global git environment

[shahmishal]

Will this overwrite local config for the user?

[shahmishal]

Also, prefer not using apple. Maybe we can use swift_test and [email protected]

[azharudd]

Will this overwrite local config for the user?

Yes

[justice-adams-apple]

Will this overwrite local config for the user?

This should only update the configuration for the git repository which is created as part of this test unless I'm misunderstanding. From the git config documentation

When writing, the new value is written to the repository local configuration file by default, and options --system, --global, --worktree, --file can be used to tell the command to write to that location (you can say --local but that is the default).

Also in the output of the error message:
Omit --global to set the identity only in this repository.

As for using the environment variables vs calling git config itself, i have no preference

[azharudd]

If those git config commands fail, they'd be ignored (because we are running them through call_quietly), and we'd still run into the original issue?

[justice-adams-apple]

@azharudd The commands will raise an exception

def call_quietly(*args, **kwargs):
    kwargs['stderr'] = subprocess.STDOUT
    try:
        subprocess.check_output(*args, **kwargs)
    except subprocess.CalledProcessError as e:
        raise CallQuietlyException(command=e.cmd, returncode=e.returncode,
                                   output=e.stdout) from e

call_quietly is intended to suppress stdout from what I'm gathering, not suppress exceptions (a bit confusing)

[azharudd]

Instead of executing those git commands, an alternative would be to set the corresponding environment variables.

os.environ['GIT_AUTHOR_NAME'] = 'swift_test'
os.environ['GIT_COMMITTER_NAME'] = 'swift_test'
os.environ['GIT_AUTHOR_EMAIL'] = '<[email protected]>'
os.environ['GIT_COMMITTER_EMAIL'] = '<[email protected]>'

This could be done within that function, and it also doesn't affect the git config.

[justice-adams-apple]

@swift-ci test

[justice-adams-apple]

@swift-ci test