In commits by Simon McVittie on Oct 5, 2014, the following was added to `cgitemplate()`:

    b0a35c81 (Simon McVittie   2014-10-05  61) 	my $topurl = $config{url};
    3b8da667 (Simon McVittie   2014-10-05  62) 	if (defined $cgi && ! $config{w3mmode} && ! $config{reverse_proxy}) {
    b0a35c81 (Simon McVittie   2014-10-05  63) 		$topurl = $cgi->url;
    b0a35c81 (Simon McVittie   2014-10-05  64) 	}

I am trying to determine what was intended by this change.  The variable `$topurl` is not used again in this function, so this is essentially dead code.
--[[blipvert]]

> If you look at `git log -p IkiWiki/CGI.pm` you'll see that *at the time*, `$topurl`
> was used further down the function. Later in the branch, [commit 33f6026
"In html5 mode, generate a host- or protocol-relative <base> for the
CGI"](http://source.ikiwiki.branchable.com/?p=source.git;a=commit;h=33f60260b233d0310ce6dd4304304a516595b906)
> made this conditional on `! $config{html5}`.
>
> Somewhat later,
> [commit 490a1ec
"Always produce HTML5 doctype and new attributes, but not new
elements"](http://source.ikiwiki.branchable.com/?p=source.git;a=commit;h=490a1eca7bed841848765b495a73fbc56e4808f4)
> repurposed `$config{html5}` from "use HTML5" to "use new HTML5 elements" -
> which meant that [commit a052771
"Now that we're always using HTML5, <base href> can be
relative"](http://source.ikiwiki.branchable.com/?p=source.git;a=commit;h=a05277128732beb351aa696c49d337086414ffb6)
> could remove the only code that used `$topurl`.
>
> You are correct to say that computing `$topurl` is now dead code, and I
> have removed it. [[done]] --[[smcv]]