fix spurious http cache bug: sometimes last-modified headers is generated using non-english local, which ends up in a date that twisted can't parse and make it feels the page may be cached while it may not

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−\.svn
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−^build$
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−^dist$
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−\.pyc$
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−\.pyo$
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−\.bak$
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−\.old$
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−\~$
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−\#.*?\#$
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−\.swp$
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−^doc/book/en/apidoc$