I believe this could be worked around simply by re-enabling that field and allowing the user to specify an email there by hand, making a note that the OpenID provider's email is used by default.
-Here's the dumbest [[!taglink patch]] that actually fixes the problem for me:
+[[!template id=gitbranch branch=anarcat/openid_email author="[[anarcat]]"]]
-[[!format diff """
-diff --git a/IkiWiki/Plugin/openid.pm b/IkiWiki/Plugin/openid.pm
-index e3b9982..df87ba3 100644
---- a/IkiWiki/Plugin/openid.pm
-+++ b/IkiWiki/Plugin/openid.pm
-@@ -104,7 +104,6 @@ sub formbuilder_setup (@) {
- size => 1, force => 1,
- fieldset => "login",
- comment => $session->param("name"));
-- $form->field(name => "email", type => "hidden");
- }
- }
-
-"""]]
+The dumbest [[!taglink patch]] that actually fixes the problem for me is in the branch mentionned here.
It would probably be better to add a comment on the field as indicated above, but it's a good proof of concept.