git_bare: Add support for filtered content with Git >= 2.21
Git 2.21 changes the error message raised by git-fsck when an object hash does not match the content: https://git.kernel.org/pub/scm/git/git.git/commit/?id=01f8d5948a7f370c42d9fe2deb724139a1bfcb7b
Related to swh/infra/sysadm-environment#3412 (closed)
Migrated from D5940 (view on Phabricator)