I wrote:

> I thought I was going crazy, but I eventually caught it.

No, I was going crazy.

> + [ 6b034f83536f7478368b3838c3b4e7ac != 6b034f83536f7478368b3838c3b4e7ac ]
> + [ yes ]

If I hadn't been tired I'd have realized that what I was looking for
was updated_file=yes not the test of its value.

So there is no bug in sh or test.  Sorry for the noise.

--sjg