shejialuo [off-list ref] writes:

The reason why "git refs verify" will report this error is that in the
code implementation, I have to iterate every file in the filesystem. So
it's convenient for me to do the following:

    if (check_refname_format(iter->basename, REFNAME_ALLOW_ONELEVEL)) {
        ret = fsck_report(...);
    }

It may be convenient, but I think it is wrong.  HEAD may be allowed
at the top, but refs/heads/HEAD is not, and checking only the single
level name as you descend into .git/refs directory hierarchy and
find files would not be a good design to begin with (and it would
not work if your backend is reftable).