receive-pack: use worktree HEAD for updateInstead

receive-pack: use worktree HEAD for updateInstead

When a bare repo has linked worktrees, and its HEAD points to an unborn branch,
pushing to a wt branch with updateInstead fails and rejects the push, even if
the wt is clean. This happens because HEAD is checked only for the bare repo
context, instead of the wt.

Remove head_has_history and check for worktree->head_oid which does
have the correct HEAD of the wt.

Update the test added by Runxi's patch to expect success.

Signed-off-by: Pablo Sabater <pabloosabaterr@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>