This keeps git operations working even when PATH is modified, e.g. `brew
update` will work even though Homebrew runs the command explicitly
without `/usr/local/bin` in PATH.
Additionally, this inserts a blank value for `credential.*.helper` to
instruct git to ignore previously configured credential helpers, i.e.
those that might have been set up in system configuration files. We do
this because otherwise, git will store the credential obtained from gh
in every other credential helper in the chain, which we want to avoid.
Before:
git config --global credential.https://github.com.helper '!gh auth git-credential'
After:
git config --global credential.https://github.com.helper ''
git config --global --add credential.https://github.com.helper '!/path/to/gh auth git-credential'
Old message:
read-only token in GH_TOKEN cannot be modified
This message was vague and some users did not understand that this
refers to the value that is read from environment variables.
New message:
$ GH_TOKEN=123 ghd auth login -h github.com
The value of the GH_TOKEN environment variable is being used for authentication.
To have GitHub CLI store credentials instead, first clear the value from the environment.
Adding GITHUB_TOKEN & GITHUB_ENTERPRISE_TOKEN support orthogonal to
Config was getting out of hand, especially in `auth` commands that
adjust their messaging and error status based on the presence of these
environment variables.
The new approach builds in support for tokens from environment straight
into Config object by composition. Thus, commands need not ever be
concerned with any specific environment variables.
