bug#7877: sleep takes undocumented hex args

[Voelker, Bernhard]

Jim Meyering wrote:
> That's an artifact of GNU sleep using strtod, which means "inf" and
> "INFINITY" are also accepted:
> 
>     $ timeout 1 sleep inf
>     [Exit 124]

what's wrong with `sleep inf`?

Have a nice day,
Berny