git -- Multiple vulnerabilities

This release contains 2 security fixes:
CVE-2022-39253

   When relying on the `--local` clone optimization, Git dereferences
   symbolic links in the source repository before creating hardlinks
   (or copies) of the dereferenced link in the destination repository.
   This can lead to surprising behavior where arbitrary files are
   present in a repository's `$GIT_DIR` when cloning from a malicious
   repository.

   Git will no longer dereference symbolic links via the `--local`
   clone mechanism, and will instead refuse to clone repositories that
   have symbolic links present in the `$GIT_DIR/objects` directory.

   Additionally, the value of `protocol.file.allow` is changed to be
   "user" by default.

CVE-2022-39260

   An overly-long command string given to `git shell` can result in
   overflow in `split_cmdline()`, leading to arbitrary heap writes and
   remote code execution when `git shell` is exposed and the directory
   `$HOME/git-shell-commands` exists.

   `git shell` is taught to refuse interactive commands that are
   longer than 4MiB in size. `split_cmdline()` is hardened to reject
   inputs larger than 2GiB.