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I saw this conjugation in the title of a novel/animated feature: 夜は短し歩けよ乙女
The reason why I suspect it is a conjugation is that, on the Wiki page, the kana is laid out as よるはみじかしあるけよおとめ. This makes me believe that 短し is not a different word, but instead 短い in a rare, conjugated form.
The question is: What is that conjugation? Is it a classical form of Japanese adjectival conjugation? If so, does it only apply to い-adjectives?