Bugfix F5 'plain' login form
Fixes #351 (closed).
It turns out that the "plain auth form" for F5 has been broken since 0b47ea18. (This form is used as a stand-in when the server fails to provide a real HTML login form, and only gives a JavaScript mess that dynamically creates a form.)
@dwmw2 probably didn't notice this when making that commit, because
a07bbbcd had previously fixed the other
places where a form with no auth_id
could be created.
This ensures that the "plain auth form" has its auth_id
set, and adds test
coverage of this form to f5-auth-and-config
.