Pages under templates/ are invalid (in fact, not only invalid, but also not well-formed) xhtml pages.
This problem is especially serious when you change extension from .html to .xhtml in ikiwiki.setup and use Firefox. Since Firefox will display a error message only for not well-formed application/xhtml+xml pages.
It seems that HTML::Template also support
<!--Variable--> syntax instead
<Variable>. Chaning to this syntax will solve this problem, I guess.
Even if changed to
<!-- TMPL_VAR --> style, the problem may still exist if the template contains if else block.
Maybe just encode all < and > when compling pages within the templates folder will solve this problem.
I never noticed this bug, since it only happens if the htmlscrubber is disabled. --Joey