Suppressing filter-branch warning

Hello there,

What did you do before the bug happened? (Steps to reproduce your issue)
git filter-branch -f --env-filter '' --tag-name-filter cat -- HEAD

What did you expect to happen? (Expected behavior)
See below (difference).

What happened instead? (Actual behavior)
When using git filter-branch, the following message is shown:

----------8<-----------------------------------------------------
WARNING: git-filter-branch has a glut of gotchas generating mangled history
         rewrites.  Hit Ctrl-C before proceeding to abort, then use an
         alternative filtering tool such as 'git filter-repo'
         (https://github.com/newren/git-filter-repo/) instead.  See the
         filter-branch manual page for more details; to squelch this warning,
         set FILTER_BRANCH_SQUELCH_WARNING=1.
----------8<-----------------------------------------------------

You can suppress this by setting the environment variable shown.

What's different between what you expected and what actually happened?

Normally, when git introduces this kind of change, there is a
git config variable that one can set to suppress it.
That way one has fine grade control when to suppress it (one repo only...globally).

Anything else you want to add:

-/-

Please review the rest of the bug report below.
You can delete any lines you don't wish to share.


[System Info]
git version:
git version 2.29.0
cpu: x86_64
no commit associated with this build
sizeof-long: 8
sizeof-size_t: 8
shell-path: /bin/sh
uname: Linux 4.19.0-10-amd64 #1 SMP Debian 4.19.132-1 (2020-07-24) x86_64
compiler info: gnuc: 8.3
libc info: glibc: 2.28
$SHELL (typically, interactive shell): /bin/bash