I'm doing a (belated) update from a version before emailauth was available,
and I get the error:

    Failed to load plugin IkiWiki::Plugin::emailauth: Not enough arguments for IkiWiki::cgi_getsession

and sure enough, emailauth.pm line 175 has

    my $session=IkiWiki::cgi_getsession();

while `cgi_getsession` is declared in CGI.pm as

    sub cgi_getsession ($) {
        my $q=shift;
        ...

and browsing through git history, it looks like it has always been that way.
Now, I have some local mods merged in, so it is possible one of them has
broken something, but before I begin questioning my sanity, just by looking
at these lines in the unmodified ikiwiki repo, um, has this ever worked?
And, why?