Revert @JeffBezanson's workaround [#2162].

@vtjnash's fix seems to work. Finger's crossed.

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Revert "try to improve the STDIN as IOStream workaround"

This reverts commit 4e8cabc337b4164b176534a85ffcfcd6578f947f.

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Revert "make STDIN an IOStream on linux when the input stream is a file"

This reverts commit 64451781dcba91dc7a5b4884afdd5eb4153d9e41.