Bug#546249: invalid HTML <FORM> within a <FORM>

[jidanni@jidanni.org]

Package: wiki.debian.org

I was trying to figure out why, when browsing the same page,
http://wiki.debian.org/DebianTaiwan/MiniDebConf2009?action=info , for
the same button presses, two different browsers would send two different
requests,

GET http://wiki.debian.org/DebianTaiwan/MiniDebConf2009?rev1=46&rev2=48 HTTP/1.0
User-Agent: Emacs-w3m/1.4.363 w3m/0.5.2

GET http://wiki.debian.org/DebianTaiwan/MiniDebConf2009?action=diff&rev2=48&rev1=46 HTTP/1.1
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.2) Gecko/20090820 Iceweasel/3.5.2 (Debian-3.5.2-1)

It turns out it is due to a "form within a form":

<form action="" method="GET"><div id="page-history"><input type="hidden"
name="action" value="diff"><form action="/DebianTaiwan/MiniDebConf2009"
method="GET" name="dbw.form">

$ validate http://wiki.debian.org/DebianTaiwan/MiniDebConf2009?action=info
*** Errors: ***
Error at line 31, character 110:  character data is not allowed here
Error at line 147, character 546:  document type does not allow element
        "FORM" here

Please do not produce such invalid HTML.

If this is in fact an upstream bug, please also notify upstream. Thank you.