Commit afe5d3d5 introduced a safety valve to symbolic-ref to disallow installing an invalid HEAD. It was accompanied by b229d18a, which changed validate_headref to require that HEAD contain a pointer to refs/heads/ instead of just refs/. Therefore, the safety valve also checked for refs/heads/.
As it turns out, topgit is using refs/top-bases/ in HEAD, leading us to re-loosen (at least temporarily) the validate_headref check made in b229d18a. This patch does the corresponding loosening for the symbolic-ref safety valve, so that the two are in agreement once more.
Signed-off-by: Jeff King <email@example.com> Signed-off-by: Junio C Hamano <firstname.lastname@example.org>