pub fn git_command(repo: &Path) -> CommandExpand description
A git command pinned to repo and stripped of every inherited
variable that could redirect it somewhere else.
Use this for every production git invocation instead of building
Command::new("git") directly. GIT_EXEC_PATH is deliberately left
alone: it only locates git’s own helper binaries and cannot change
which repository git acts on.
Clearing GIT_CONFIG_COUNT is sufficient to neutralize any inherited
GIT_CONFIG_KEY_n/GIT_CONFIG_VALUE_n pair — git only reads those when
the count is set — so they need no separate sweep.