Fixes the following security issue:
CVE-2022-24765:
On multi-user machines, Git users might find themselves unexpectedly in
a Git worktree, e.g. when there is a scratch space (`/scratch/`) intended
for all users and another user created a repository in `/scratch/.git`.
Merely having a Git-aware prompt that runs `git status` (or `git diff`)
and navigating to a directory which is supposedly not a Git worktree, or
opening such a directory in an editor or IDE such as VS Code or Atom, will
potentially run commands defined by that other user via
`/scratch/.git/config`.
https://www.openwall.com/lists/oss-security/2022/04/12/7
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
832107c6dc