bug#57306: guix pull to old commit fails due to unsupported manifest format

[Arun Isaac]

When I guix pull to 6f75565b4ec3b8a7247699c327a3b3196c787f76, activate
the profile and run guix describe, it fails with an "unsupported
manifest format" error.

--8<---------------cut here---------------start------------->8---
$ guix pull --commit=6f75565b4ec3b8a7247699c327a3b3196c787f76 -p
/tmp/test
$ source /tmp/test/etc/profile
$ guix describe
guix describe: error: unsupported manifest format
--8<---------------cut here---------------end--------------->8---

This happens because my guix-daemon writes a version 4 manifest and the
guix from commit 6f75565b4ec3b8a7247699c327a3b3196c787f76 only
understands a version 3 manifest.

This may be related to https://issues.guix.gnu.org/56545